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Fernando Meo
最後のアクティビティ: 2024 年 12 月 19 日 13:48

Solution to slow execution of "uigetfile" function with an enormous number of files in a folder

If you have a folder with an enormous number of files and want to use the uigetfile function to select specific files, you may have noticed a significant delay in displaying the file list.

Thanks to the assistance from MathWorks support, an interesting behavior was observed.

For example, if a folder such as Z:\Folder1\Folder2\data contains approximately 2 million files, and you attempt to use uigetfile to access files with a specific extension (e.g., *.ext), the following behavior occurs:

Method 1: This takes minutes to show me the list of all files

[FileName, PathName] = uigetfile('Z:\Folder1\Folder2\data\*.ext',  'File selection');

Method 2: This takes less than a second to display all files.

[FileName, PathName] = uigetfile('*.ext', 'File selection','Z:\Folder1\Folder2\data');

Method 3: This method also takes minutes to display the file list. What is intertesting is that this method is the same as Method 2, except that a file seperator "\" is added at the end of the folder string.

[FileName, PathName] = uigetfile('*.ext', 'File selection','Z:\Folder1\Folder2\data\');

I was informed that the Mathworks development team has been informed of this strange behaviour.

I am using 2023a, but think this should be the same for newer versions.

Fernando Meo
最後のアクティビティ: 2024 年 12 月 18 日 16:27

Solution to slow execution of "uigetfile" function with an enormous number of files in a folder

This post is more of a "tips and tricks" guide than a question.

If you have a folder with an enormous number of files and want to use the uigetfile function to select specific files, you may have noticed a significant delay in displaying the file list.

Thanks to the assistance from MathWorks support, an interesting behavior was observed.

Method 1: This takes minutes to show me the list of all files

[FileName, PathName] = uigetfile('Z:\Folder1\Folder2\data\*.ext',  'File selection');

Method 2: This takes less than a second to display all files.

[FileName, PathName] = uigetfile('*.ext', 'File selection','Z:\Folder1\Folder2\data');

[FileName, PathName] = uigetfile('*.ext', 'File selection','Z:\Folder1\Folder2\data\');

I was informed that the Mathworks development team has been informed of this strange behaviour.

I am using 2023a, but think this should be the same for newer versions.

Zhaoxu Liu / slandarer
最後のアクティビティ: 2024 年 12 月 16 日 16:49

Christmas Tree for Matlaber : Rotating With Falling Snowflakes

Christmas is coming, here are two dynamic Christmas tree drawing codes:

Crystal XMas Tree

function XmasTree2024_1
fig = figure('Units','normalized', 'Position',[.1,.1,.5,.8],...
    'Color',[0,9,33]/255, 'UserData',40 + [60,65,75,72,0,59,64,57,74,0,63,59,57,0,1,6,45,75,61,74,28,57,76,57,1,1]);
axes('Parent',fig, 'Position',[0,-1/6,1,1+1/3], 'UserData',97 + [18,11,0,13,3,0,17,4,17],...
      'XLim',[-1.5,1.5], 'YLim',[-1.5,1.5], 'ZLim',[-.2,3.8], 'DataAspectRatio', [1,1,1], 'NextPlot','add',...
      'Projection','perspective', 'Color',[0,9,33]/255, 'XColor','none', 'YColor','none', 'ZColor','none')
%% Draw Christmas tree
F = [1,3,4;1,4,5;1,5,6;1,6,3;...
    2,3,4;2,4,5;2,5,6;2,6,3];
dP = @(V) patch('Faces',F, 'Vertices',V, 'FaceColor',[0 71 177]./255,...
    'FaceAlpha',rand(1).*0.2+0.1, 'EdgeColor',[0 71 177]./255.*0.8,...
    'EdgeAlpha',0.6, 'LineWidth',0.5, 'EdgeLighting','gouraud', 'SpecularStrength',0.3);
r = .1; h = .8; 
V0 = [0,0,0; 0,0,1; 0,r,h; r,0,h; 0,-r,h; -r,0,h];
% Rotation matrix
Rx = @(V, theta) V*[1 0 0; 0 cos(theta) sin(theta); 0 -sin(theta) cos(theta)];
Rz = @(V, theta) V*[cos(theta) sin(theta) 0;-sin(theta) cos(theta) 0; 0 0 1];
N = 180; Vn = zeros(N, 3); eval(char(fig.UserData))
for i = 1:N
    tV = Rz(Rx(V0.*(1.2 - .8.*i./N + rand(1).*.1./i^(1/5)), pi/3.*(1 - .6.*i./N)), i.*pi/8.1 + .001.*i.^2) + [0,0,.016.*i];
    dP(tV); Vn(i,:) = tV(2,:);
end
scatter3(Vn(:,1).*1.02,Vn(:,2).*1.02,Vn(:,3).*1.01, 30, 'w', 'Marker','*', 'MarkerEdgeAlpha',.5)
%% Draw Star of Bethlehem
w = .3; R = .62; r = .4; T = (1/8:1/8:(2 - 1/8)).'.*pi;
V8 = [ 0, 0, w;  0, 0,-w;
       1, 0, 0;  0, 1, 0; -1, 0, 0;  0,-1,0;
       R, R, 0; -R, R, 0; -R,-R, 0;  R,-R,0;
       cos(T).*r, sin(T).*r, T.*0];
F8 = [1,3,25; 1,3,11; 2,3,25; 2,3,11; 1,7,11; 1,7,13; 2,7,11; 2,7,13;
      1,4,13; 1,4,15; 2,4,13; 2,4,15; 1,8,15; 1,8,17; 2,8,15; 2,8,17;
      1,5,17; 1,5,19; 2,5,17; 2,5,19; 1,9,19; 1,9,21; 2,9,19; 2,9,21;
      1,6,21; 1,6,23; 2,6,21; 2,6,23; 1,10,23; 1,10,25; 2,10,23; 2,10,25];
V8 = Rx(V8.*.3, pi/2) + [0,0,3.5];
patch('Faces',F8, 'Vertices',V8, 'FaceColor',[255,223,153]./255,...
      'EdgeColor',[255,223,153]./255, 'FaceAlpha', .2)
%% Draw snow
sXYZ = rand(200,3).*[4,4,5] - [2,2,0];
sHdl1 = plot3(sXYZ(1:90,1),sXYZ(1:90,2),sXYZ(1:90,3), '*', 'Color',[.8,.8,.8]);
sHdl2 = plot3(sXYZ(91:200,1),sXYZ(91:200,2),sXYZ(91:200,3), '.', 'Color',[.6,.6,.6]);
annotation(fig,'textbox',[0,.05,1,.09], 'Color',[1 1 1], 'String','Merry Christmas Matlaber',...
    'HorizontalAlignment','center', 'FontWeight','bold', 'FontSize',48,...
    'FontName','Times New Roman', 'FontAngle','italic', 'FitBoxToText','off','EdgeColor','none');
% Rotate the Christmas tree and let the snow fall
for i=1:1e8
    sXYZ(:,3) = sXYZ(:,3) - [.05.*ones(90,1); .06.*ones(110,1)];
    sXYZ(sXYZ(:,3)<0, 3) = sXYZ(sXYZ(:,3) < 0, 3) + 5;
    sHdl1.ZData = sXYZ(1:90,3); sHdl2.ZData = sXYZ(91:200,3);
    view([i,30]); drawnow; pause(.05)
end
end

Curved XMas Tree

function XmasTree2024_2
fig = figure('Units','normalized', 'Position',[.1,.1,.5,.8],...
    'Color',[0,9,33]/255, 'UserData',40 + [60,65,75,72,0,59,64,57,74,0,63,59,57,0,1,6,45,75,61,74,28,57,76,57,1,1]);
axes('Parent',fig, 'Position',[0,-1/6,1,1+1/3], 'UserData',97 + [18,11,0,13,3,0,17,4,17],...
      'XLim',[-6,6], 'YLim',[-6,6], 'ZLim',[-16, 1], 'DataAspectRatio', [1,1,1], 'NextPlot','add',...
      'Projection','perspective', 'Color',[0,9,33]/255, 'XColor','none', 'YColor','none', 'ZColor','none')
%% Draw Christmas tree
[X,T] = meshgrid(.4:.1:1, 0:pi/50:2*pi);
XM = 1 + sin(8.*T).*.05;
X = X.*XM; R = X.^(3).*(.5 + sin(8.*T).*.02);
dF = @(R, T, X) surf(R.*cos(T), R.*sin(T), -X, 'EdgeColor',[20,107,58]./255,...
    'FaceColor', [20,107,58]./255, 'FaceAlpha',.2, 'LineWidth',1);
CList = [254,103,110; 255,191,115; 57,120,164]./255;
for i = 1:5
    tR = R.*(2 + i); tT = T+i; tX = X.*(2 + i) + i;
    SFHdl = dF(tR, tT, tX);
    [~, ind] = sort(SFHdl.ZData(:)); ind = ind(1:8);
    C = CList(randi([1,size(CList,1)], [8,1]), :);
    scatter3(tR(ind).*cos(tT(ind)), tR(ind).*sin(tT(ind)), -tX(ind), 120, 'filled',...
        'CData', C, 'MarkerEdgeColor','none', 'MarkerFaceAlpha',.3)
    scatter3(tR(ind).*cos(tT(ind)), tR(ind).*sin(tT(ind)), -tX(ind), 60, 'filled', 'CData', C)
end
%% Draw Star of Bethlehem
Rx = @(V, theta) V*[1 0 0; 0 cos(theta) sin(theta); 0 -sin(theta) cos(theta)];
% Rz = @(V, theta) V*[cos(theta) sin(theta) 0;-sin(theta) cos(theta) 0; 0 0 1];
w = .3; R = .62; r = .4; T = (1/8:1/8:(2 - 1/8)).'.*pi;
V8 = [ 0, 0, w;  0, 0,-w;
       1, 0, 0;  0, 1, 0; -1, 0, 0;  0,-1,0;
       R, R, 0; -R, R, 0; -R,-R, 0;  R,-R,0;
       cos(T).*r, sin(T).*r, T.*0];
F8 = [1,3,25; 1,3,11; 2,3,25; 2,3,11; 1,7,11; 1,7,13; 2,7,11; 2,7,13;
      1,4,13; 1,4,15; 2,4,13; 2,4,15; 1,8,15; 1,8,17; 2,8,15; 2,8,17;
      1,5,17; 1,5,19; 2,5,17; 2,5,19; 1,9,19; 1,9,21; 2,9,19; 2,9,21;
      1,6,21; 1,6,23; 2,6,21; 2,6,23; 1,10,23; 1,10,25; 2,10,23; 2,10,25];
V8 = Rx(V8.*.8, pi/2) + [0,0,-1.3];
patch('Faces',F8, 'Vertices',V8, 'FaceColor',[255,223,153]./255,...
      'EdgeColor',[255,223,153]./255, 'FaceAlpha', .2)
annotation(fig,'textbox',[0,.05,1,.09], 'Color',[1 1 1], 'String','Merry Christmas Matlaber',...
    'HorizontalAlignment','center', 'FontWeight','bold', 'FontSize',48,...
    'FontName','Times New Roman', 'FontAngle','italic', 'FitBoxToText','off','EdgeColor','none');
%% Draw snow
sXYZ = rand(200,3).*[12,12,17] - [6,6,16];
sHdl1 = plot3(sXYZ(1:90,1),sXYZ(1:90,2),sXYZ(1:90,3), '*', 'Color',[.8,.8,.8]);
sHdl2 = plot3(sXYZ(91:200,1),sXYZ(91:200,2),sXYZ(91:200,3), '.', 'Color',[.6,.6,.6]);
for i=1:1e8
    sXYZ(:,3) = sXYZ(:,3) - [.1.*ones(90,1); .12.*ones(110,1)];
    sXYZ(sXYZ(:,3)<-16, 3) = sXYZ(sXYZ(:,3) < -16, 3) + 17.5;
    sHdl1.ZData = sXYZ(1:90,3); sHdl2.ZData = sXYZ(91:200,3);
    view([i,30]); drawnow; pause(.05)
end
end

I wish all MATLABers a Merry Christmas in advance!

Steve Eddins
最後のアクティビティ: 2024 年 12 月 12 日 21:25

It's time to retire and replace IMSHOW

Speaking as someone with 31+ years of experience developing and using imshow, I want to advocate for retiring and replacing it.

The function imshow has behaviors and defaults that were appropriate for the MATLAB and computer monitors of the 1990s, but which are not the best choice for most image display situations in today's MATLAB. Also, the 31 years have not been kind to the imshow code base. It is a glitchy, hard-to-maintain monster.

My new File Exchange function, imview, illustrates the kind of changes that I think should be made. The function imview is a much better MATLAB graphics citizen and produces higher quality image display by default, and it dispenses with the whole fraught business of trying to resize the containing figure. Although this is an initial release that does not yet support all the useful options that imshow does, it does enough that I am prepared to stop using imshow in my own work.

The Image Processing Toolbox team has just introduced in R2024b a new image viewer called imageshow, but that image viewer is created in a special-purpose window. It does not satisfy the need for an image display function that works well with the axes and figure objects of the traditional MATLAB graphics system.

I have published a blog post today that describes all this in more detail. I'd be interested to hear what other people think.

Note: Yes, I know there is an Image Processing Toolbox function called imview. That one is a stub for an old toolbox capability that was removed something like 15+ years ago. The only thing the toolbox imview function does now is call error. I have just submitted a support request to MathWorks to remove this old stub.

Paul
最後のアクティビティ: 2024 年 12 月 15 日 20:43

Would a General Hold/Release Functionality be a Good Feature for the Symbolic Toolbox?

The int function in the Symbolic Toolbox has a hold/release functionality wherein the expression can be held to delay evaluation

syms x I

eqn = I == int(x,x,'Hold',true)

eqn =

which allows one to show the integral, and then use release to show the result

release(eqn)

ans =

I think I already submitted an enhancement request for the same functionality for symsum.

Maybe it would be nice to be able to hold/release any symbolic expression to delay the engine from doing evaluations/simplifications that it typically does. For example:

x*(x+1)/x, sin(sym(pi)/3)

ans =

If I'm trying to show a sequence of steps to develop a result, maybe I want to explicitly keep the x/x in the first case and then say "now the x in the numerator and denominator cancel and the result is ..." followed by the release command to get the final result.

Perhaps held expressions could even be nested to show a sequence of results upon subsequent releases.

Held expressions might be subject to other limitations, like maybe they can't be fplotted.

Seems like such a capability might not be useful for problem solving, but might be useful for exposition, instruction, etc.

Mike McLernon
最後のアクティビティ: 2024 年 12 月 3 日 1:06

Summarizing Bluetooth 6.0 and its High Accuracy Ranging

Hi! My name is Mike McLernon, and I’m a product marketing engineer with MathWorks. In my role, I look at the trends ongoing in the wireless industry, across lots of different standards (think 5G, WLAN, SatCom, Bluetooth, etc.), and I seek to shape and guide the software that MathWorks builds to respond to these trends. That’s all about communicating within the Mathworks organization, but every so often it’s worth communicating these trends to our audience in the world at large. Many of the people reading this are engineers (or engineers at heart), and we all want to know what’s happening in the geek world around us. I think that now is one of these times to communicate an important milestone. So, without further ado . . .

Bluetooth 6.0 is here! Announced in September by the Bluetooth Special Interest Group (SIG), it’s making more advances in its quest to create a “world without wires”. A few of the salient features in Bluetooth 6.0 are:

Channel sounding (for accurate distance measurements)
Decision-based advertising filtering (for more efficient channel scanning)
Monitoring advertisers (for improved energy efficiency when devices come into and go out of range)
Frame space updates (for both higher throughput and better coexistence management)

Bluetooth 6.0 includes other features as well, but the SIG has put special promotional emphasis on channel sounding (CS), which once upon a time was called High Accuracy Distance Measurement (HADM). The SIG has said that CS is a step towards true distance awareness, and 10 cm ranging accuracy. I think their emphasis is in exactly the right place, so let’s learn more about this technology and how it is used.

CS can be used for the following use cases:

Keyless vehicle entry, performed by communication between a key fob or phone and the car’s anchor points
Smart locks, to permit access only when an authorized device is within a designated proximity to the locks
Geofencing, to limit access to designated areas
Warehouse management, to monitor inventory and manage logistics
Asset tracking for virtually any object of interest

In the past, Bluetooth devices would use a received signal strength indicator (RSSI) measurement to infer the distance between two of them. They would assume a free space path loss on the link, and use a straightforward equation to estimate distance:

where

received power in dBm,

transmitted power in dBm,

propagation loss in dB,

distance between the two devices, in m,

Bluetooth signal wavelength, in m,

Bluetooth signal frequency, in Hz,

speed of light (3 x 1e8 m/s).

So in this method,

. But if the signal suffers more loss from multipath or shadowing, then the distance would be overestimated. Something better needed to be found.

Bluetooth 6.0 introduces not one, but two ways to accurately measure distance:

Round-trip time (RTT) measurement
Phase-based ranging (PBR) measurement

The RTT measurement method uses the fact that the Bluetooth signal time of flight (TOF) between two devices is half the RTT. It can then accurately compute the distance d as

, where c is again the speed of light. This method requires accurate measurements of the time of departure (TOD) of the outbound signal from device 1 (the Initiator), time of arrival (TOA) of the outbound signal to device 2 (the Reflector), TOD of the return signal from device 2, and TOA of the return signal to device 1. The diagram below shows the signal paths and the times.

If you want to see how you can use MATLAB to simulate the RTT method, take a look at Estimate Distance Between Bluetooth LE Devices by Using Channel Sounding and Round-Trip Timing.

The PBR method uses two Bluetooth signals of different frequencies to measure distance. These signals are simply tones – sine waves. Without going through the derivation, PBR calculates distance d as

, where

distance between the two devices, in m,

speed of light (3 x 1e8 m/s),

phase measured at the Initiator after the tone at

completes a round trip, in radians,

phase measured at the Initiator after the tone at

completes a round trip, in radians,

frequency of the first tone, in Hz,

frequency of the second tone, in Hz.

The mod() operation is needed to eliminate ambiguities in the distance calculation and the final division by two is to convert a round trip distance to a one-way distance. Because a given phase difference value can hold true for an infinite number of distance values, the mod() operation chooses the smallest distance that satisfies the equation. Also, these tones can be as close as 1 MHz apart. In that case, the maximum resolvable distance measurement is about 150 m. The plot below shows that ambiguity and repetition in distance measurement.

If you want to see how you can use MATLAB to simulate the PBR method, take a look at Estimate Distance Between Bluetooth LE Devices by Using Channel Sounding and Phase-Based Ranging.

Bluetooth 6.0 outlines RTT and PBR distance measurement methods, but CS does not mandate a specific algorithm for calculating distance estimates. This flexibility allows device manufacturers to tailor solutions to various use cases, balancing computational complexity with required accuracy and adapting to different radio environments. Examples include simple phase difference calculations and FFT-based methods.

Although Bluetooth 6.0 is now out, it is far from a finished version. The SIG is actively working through the ratification process for two major extensions:

High Data Throughput, up to 8 Mbps
5 and 6 GHz operation

See the last few minutes of this video from the SIG to learn more about these exciting future developments. And if you want to see more Bluetooth blogs, give a review of this one! Finally, if you have specific Bluetooth questions, give me a shout and let’s start a discussion!

lazymatlab
最後のアクティビティ: 2024 年 11 月 27 日

First snow this winter in Korea.

So I made this.

clear
close all
clc
% inspired from: https://www.youtube.com/watch?v=3CuUmy7jX6k
%% user parameters
h = 768;
w = 1024;
N_snowflakes = 50;
%% set figure window
figure(NumberTitle="off", ...
    name='Mat-snowfalling-lab (right click to stop)', ...
    MenuBar="none")
ax = gca;
ax.XAxisLocation = 'origin';
ax.YAxisLocation = 'origin';
axis equal
axis([0, w, 0, h])
ax.Color = 'k';
ax.XAxis.Visible = 'off';
ax.YAxis.Visible = 'off';
ax.Position = [0, 0, 1, 1];
%% first snowflake
 
ht = gobjects(1, 1);
for i=1:length(ht)
    ht(i) = hgtransform();
    ht(i).UserData = snowflake_factory(h, w);
    ht(i).Matrix(2, 4) = ht(i).UserData.y;
    ht(i).Matrix(1, 4) = ht(i).UserData.x;
    im = imagesc(ht(i), ht(i).UserData.img);
    im.AlphaData = ht(i).UserData.alpha; 
    colormap gray
end
%% falling snowflake
tic;
while true
    % add a snowflake every 0.3 seconds
    if toc > 0.3
        if length(ht) < N_snowflakes
            ht = [ht; hgtransform()];
            ht(end).UserData = snowflake_factory(h, w);
            ht(end).Matrix(2, 4) = ht(end).UserData.y;
            ht(end).Matrix(1, 4) = ht(end).UserData.x;
            im = imagesc(ht(end), ht(end).UserData.img);
            im.AlphaData = ht(end).UserData.alpha;
            colormap gray
        end
        tic;
    end
    ax.CLim = [0, 0.0005]; % prevent from auto clim
    % move snowflakes
    for i = 1:length(ht)
        ht(i).Matrix(2, 4) = ht(i).Matrix(2, 4) + ht(i).UserData.velocity;
    end
    if strcmp(get(gcf, 'SelectionType'), 'alt')
        set(gcf, 'SelectionType', 'normal')
        break
    end
    drawnow
    % delete the snowflakes outside the window
    for i = length(ht):-1:1
        if ht(i).Matrix(2, 4) < -length(ht(i).Children.CData)
            delete(ht(i))
            ht(i) = [];
        end
    end
end
%% snowflake factory
function snowflake = snowflake_factory(h, w)
radius = round(rand*h/3 + 10);
sigma = radius/6;
snowflake.velocity = -rand*0.5 - 0.1;
snowflake.x = rand*w;
snowflake.y = h - radius/3;
snowflake.img = fspecial('gaussian', [radius, radius], sigma);
snowflake.alpha = snowflake.img/max(max(snowflake.img));
end

@Dhimas Mahardika / Creating Butterflies using Mathematics Formula

Chen Lin
最後のアクティビティ: 2024 年 11 月 15 日

MATLAB Shorts Contest - Grand Prize Winners Announced!

We are thrilled to announce the grand prize winners of our MATLAB Shorts Mini Hack contest! This year, we invited the MATLAB Graphics and Charting team, the authors of the MATLAB functions used in every entry, to be our judges. After careful consideration, they have selected the top three winners:

1st place - Tim

Judge comments: Realism & detailed comments; wowed us with Manta Ray

2nd place – Jenny Bosten

Judge comments: Topical hacks : Auroras & Wind turbine; beautiful landscapes & nightscapes

3rd place - Vasilis Bellos

Judge comments: Nice algorithms & extra comments; can’t go wrong with Pumpkins

There is also an Honorable Mention - William Dean

Judge comments: Impressive spring & cubes!

In addition, after validating the votes, we are pleased to announce the top 10 participants on the leaderboard:

@Tim / Manta Ray

@Safin / Happy Shaping!!!

@Kaustubh / Fourier Circle Art

@William Dean / Trefoil Spring

@Malik / Moonlit Night

@Sonesson / Rubix Cube

@Zhaoxu Liu / slandarer / Dragon in the deep sea

@Jenny Bosten / Lake view to the North

@Matteo / Trapped particles++

Congratulations to all! Your creativity and skills have inspired many of us to explore and learn new skills, and make this contest a big success!

Hans Scharler
最後のアクティビティ: 2024 年 11 月 11 日

[cross posted] List of niche features you want in generic Matlab

Reddit Link: https://www.reddit.com/r/matlab/comments/1gojfod/list_of_niche_features_you_want_in_generic_matlab/

Chen Lin
最後のアクティビティ: 2024 年 11 月 6 日

An interview with Jenny Bosten

Dear MATLAB contest enthusiasts,

Welcome to the third installment of our interview series with top contest participants! This time we had the pleasure of talking to our all-time rock star – @Jenny Bosten. Every one of her entries is a masterpiece, demonstrating a deep understanding of the relationship between mathematics and aesthetics. Even Cleve Moler, the original author of MATLAB, is impressed and wrote in his blog: "Her code for Time Lapse of Lake View to the West shows she is also a wizard of coordinate systems and color maps."

The interview has been published on the MATLAB Community Blog. We highly encourage

you to read it to learn more about Jenny’s journey, her creative process, and her favorite entries.

Question: Who would you like to see featured in our next interview? Let us know your thoughts in the comments!

Image Analyst
最後のアクティビティ: 2024 年 11 月 7 日

Shade between curves

It would be nice to have a function to shade between two curves. This is a common question asked on Answers and there are some File Exchange entries on it but it's such a common thing to want to do I think there should be a built in function for it. I'm thinking of something like

plotsWithShading(x1, y1, 'r-', x2, y2, 'b-', 'ShadingColor', [.7, .5, .3], 'Opacity', 0.5);

So we can specify the coordinates of the two curves, and the shading color to be used, and its opacity, and it would shade the region between the two curves where the x ranges overlap. Other options should also be accepted, like line with, line style, markers or not, etc. Perhaps all those options could be put into a structure as fields, like

plotsWithShading(x1, y1, options1, x2, y2, options2, 'ShadingColor', [.7, .5, .3], 'Opacity', 0.5);

the shading options could also (optionally) be a structure. I know it can be done with a series of other functions like patch or fill, but it's kind of tricky and not obvious as we can see from the number of questions about how to do it.

Does anyone else think this would be a convenient function to add?

Matteo / Trapped particles++

Chen Lin
最後のアクティビティ: 2024 年 11 月 7 日

Week 4 Winners Announced! Final Week to Vote on Entries

Over the past 4 weeks, 250+ creative short movies have been crafted. We had a lot of fun and, more importantly, learned new skills from each other! Now it’s time to announce week 4 winners.

Nature:

Malik / Moonlit Night

Jenny Bosten / Lake view to the North

Timothy / Refraction

Teodo / Whispers of the Ocean's Breeze

3D:

Vasilis Bellos / Ripples 3D

William Dean / Trefoil Spring

Seamless loop:

博正 / Hue phase loop complex function graph

Holiday:

Michael C. / Pumpkin Pixels

Fractal:

Greg Hungerford / Distorted Newton's Method Fractal IV

Congratulations! Each of you won your choice of a T-shirt, a hat, or a coffee mug. We will contact you after the contest ends.

Weekly Special Prizes

Sonesson / My Short Rubix Adventure

Teodo / MATLAB's Fractal Art

Vasilis Bellos / Masking 3D Surfaces and Carving Pumpkins - A Halloween Special!

Thank you for sharing your tips & tricks with the community. These great technical articles will benefit community users for many years. You won a limited-edition pair of MATLAB Shorts!

In week 5, let’s take a moment to sit back, explore all of the interesting entries, and cast your votes. Reflect what you have learned or which entries you like most. Share anything in our Discussions area! There is still time to win our limited-edition MATLAB Shorts.

cui,xingxing
最後のアクティビティ: 2024 年 12 月 11 日 1:04

MATLAB is looking forward to having an intelligent AI programming assistant similar to GitHub Copilot

In the past two years, large language models have brought us significant changes, leading to the emergence of programming tools such as GitHub Copilot, Tabnine, Kite, CodeGPT, Replit, Cursor, and many others. Most of these tools support code writing by providing auto-completion, prompts, and suggestions, and they can be easily integrated with various IDEs.

As far as I know, aside from the MATLAB-VSCode/MatGPT plugin, MATLAB lacks such AI assistant plugins for its native MATLAB-Desktop, although it can leverage other third-party plugins for intelligent programming assistance. There is hope for a native tool of this kind to be built-in.

Zhihao
最後のアクティビティ: 2024 年 12 月 27 日 21:27

Several fancy functions.

Hi everyone, I wrote several fancy functions that may help your coding experience, since they are in very early developing stage, I will be thankful if anyone could try them and give some feedbacks. Currently I have following:

fstr: a Python f-string like expression
printf: an easy to use fprintf function, accepts multiple arguments with seperator, end string control.

I will bring more functions or packages like logger when I am available.

The code is open sourced at GitHub with simple examples: https://github.com/bentrainer/MMGA

Lev
最後のアクティビティ: 2024 年 11 月 1 日

Cheat-Sheet of fundamental MATLAB expressions

MATLAB Comprehensive commands list:

clc - clears command window, workspace not affected
clear - clears all variables from workspace, all variable values are lost
diary - records into a file almost everything that appears in command window.
exit - exits the MATLAB session
who - prints all variables in the workspace
whos - prints all variables in current workspace, with additional information.

Ch. 2 - Basics:

Mathematical constants: pi, i, j, Inf, Nan, realmin, realmax
Precedence rules: (), ^, negation, */, +-, left-to-right
and, or, not, xor
exp - exponential
log - natural logarithm
log10 - common logarithm (base 10)
sqrt (square root)

fprintf("final amount is %f units.", amt);
can have: %f, %d, %i, %c, %s
%f - fixed-point notation
%e - scientific notation with lowercase e
disp - outputs to a command window
% - fieldWith.precision convChar

MyArray = [startValue : IncrementingValue : terminatingValue]

Linspace

linspace(xStart, xStop, numPoints)

% xStart: Starting value

% xStop: Stop value

% numPoints: Number of linear-spaced points, including xStart and xStop

% Outputs a row array with the resulting values

Logspace

logspace(powerStart, powerStop, numPoints)

% powerStart: Starting value 10^powerStart

% powerStop: Stop value 10^powerStop

% numPoints: Number of logarithmic spaced points, including 10^powerStart and 10^powerStop

% Outputs a row array with the resulting values

Transpose an array with []'

Element-Wise Operations

rowVecA = [1, 4, 5, 2];

rowVecB = [1, 3, 0, 4];

sumEx = rowVecA + rowVecB % Element-wise addition

diffEx = rowVecA - rowVecB % Element-wise subtraction

dotMul = rowVecA .* rowVecB % Element-wise multiplication

dotDiv = rowVecA ./ rowVecB % Element-wise division

dotPow = rowVecA .^ rowVecB % Element-wise exponentiation

isinf(A) - check if the array elements are infinity
isnan(A)

Rounding Functions

ceil(x) - rounds each element of x to nearest integer >= to element
floor(x) - rounds each element of x to nearest integer <= to element
fix(x) - rounds each element of x to nearest integer towards 0
round(x) - rounds each element of x to nearest integer. if round(x, N), rounds N digits to the right of the decimal point.
rem(dividend, divisor) - produces a result that is either 0 or has the same sign as the dividen.
mod(dividend, divisor) - produces a result that is either 0 or same result as divisor.
Ex: 12/2, 12 is dividend, 2 is divisor
sum(inputArray) - sums all entires in array

Complex Number Functions

abs(z) - absolute value, is magnitude of complex number (phasor form r*exp(j0)
angle(z) - phase angle, corresponds to 0 in r*exp(j0)
complex(a,b) - creates complex number z = a + jb
conj(z) - given complex conjugate a - jb
real(z) - extracts real part from z
imag(z) - extracts imaginary part from z
unwrap(z) - removes the modulus 2pi from an array of phase angles.

Statistics Functions

mean(xAr) - arithmetic mean calculated.
std(xAr) - calculated standard deviation
median(xAr) - calculated the median of a list of numbers
mode(xAr) - calculates the mode, value that appears most often
max(xAr)
min(xAr)
If using &&, this means that if first false, don't bother evaluating second

Random Number Functions

rand(numRand, 1) - creates column array
rand(1, numRand) - creates row array, both with numRand elements, between 0 and 1
randi(maxRandVal, numRan, 1) - creates a column array, with numRand elements, between 1 and maxRandValue.
randn(numRand, 1) - creates a column array with normally distributed values.
Ex: 10 * rand(1, 3) + 6
"10*rand(1, 3)" produces a row array with 3 random numbers between 0 and 10. Adding 6 to each element results in random values between 6 and 16.
randi(20, 1, 5)
Generates 5 (last argument) random integers between 1 (second argument) and 20 (first argument). The arguments 1 and 5 specify a 1 × 5 row array is returned.

Discrete Integer Mathematics

primes(maxVal) - returns prime numbers less than or equal to maxVal
isprime(inputNums) - returns a logical array, indicating whether each element is a prime number
factor(intVal) - returns the prime factors of a number
gcd(aVals, bVals) - largest integer that divides both a and b without a remainder
lcm(aVals, bVals) - smallest positive integer that is divisible by both a and b
factorial(intVals) - returns the factorial
perms(intVals) - returns all the permutations of the elements int he array intVals in a 2D array pMat.
randperm(maxVal)
nchoosek(n, k)
binopdf(x, n, p)

Concatenation

cat, vertcat, horzcat
Flattening an array, becomes vertical: sampleList = sampleArray ( : )

Dimensional Properties of Arrays

nLargest = length(inArray) - number of elements along largest dimension
nDim = ndims(inArray)
nArrElement = numel(inArray) - nuber of array elements
[nRow, nCol] = size(inArray) - returns the number of rows and columns on array. use (inArray, 1) if only row, (inArray, 2) if only column needed
aZero = zeros(m, n) - creates an m by n array with all elements 0
aOnes = ones(m, n) - creates an m by n array with all elements set to 1
aEye = eye(m, n) - creates an m by n array with main diagonal ones
aDiag = diag(vector) - returns square array, with diagonal the same, 0s elsewhere.
outFlipLR = fliplr(A) - Flips array left to right.
outFlipUD = flipud(A) - Flips array upside down.
outRot90 = rot90(A) - Rotates array by 90 degrees counter clockwise around element at index (1,1).
outTril = tril(A) - Returns the lower triangular part of an array.
outTriU = triu(A) - Returns the upper triangular part of an array.
arrayOut = repmat(subarrayIn, mRow, nCol), creates a large array by replicating a smaller array, with mRow x nCol tiling of copies of subarrayIn
reshapeOut - reshape(arrayIn, numRow, numCol) - returns array with modifid dimensions. Product must equal to arrayIn of numRow and numCol.
outLin = find(inputAr) - locates all nonzero elements of inputAr and returns linear indices of these elements in outLin.
[sortOut, sortIndices] = sort(inArray) - sorts elements in ascending order, results result in sortOut. specify 'descend' if you want descending order. sortIndices hold the sorted indices of the array elements, which are row indices of the elements of sortOut in the original array
[sortOut, sortIndices] = sortrows(inArray, colRef) - sorts array based on values in column colRef while keeping the rows together. Bases on first column by default.
isequal(inArray1, inarray2, ..., inArrayN)
isequaln(inArray1, inarray2, ..., inarrayn)

arrayChar = ischar(inArray) - ischar tests if the input is a character array.
arrayLogical = islogical(inArray) - islogical tests for logical array.
arrayNumeric = isnumeric(inArray) - isnumeric tests for numeric array.
arrayInteger = isinteger(inArray) - isinteger tests whether the input is integer type (Ex: uint8, uint16, ...)
arrayFloat = isfloat(inArray) - isfloat tests for floating-point array.
arrayReal= isreal(inArray) - isreal tests for real array.
objIsa = isa(obj,ClassName) - isa determines whether input obj is an object of specified class ClassName.
arrayScalar = isscalar(inArray) - isscalar tests for scalar type.
arrayVector = isvector(inArray) - isvector tests for a vector (a 1D row or column array).
arrayColumn = iscolumn(inArray) - iscolumn tests for column 1D arrays.
arrayMatrix = ismatrix(inArray) - ismatrix returns true for a scalar or array up to 2D, but false for an array of more than 2 dimensions.
arrayEmpty = isempty(inArray) - isempty tests whether inArray is empty.
primeArray = isprime(inArray) - isprime returns a logical array primeArray, of the same size as inArray. The value at primeArray(index) is true when inArray(index) is a prime number. Otherwise, the values are false.
finiteArray = isfinite(inArray) - isfinite returns a logical array finiteArray, of the same size as inArray. The value at finiteArray(index) is true when inArray(index) is finite. Otherwise, the values are false.
infiniteArray = isinf(inArray) - isinf returns a logical array infiniteArray, of the same size as inArray. The value at infiniteArray(index) is true when inArray(index) is infinite. Otherwise, the values are false.
nanArray = isnan(inArray) - isnan returns a logical array nanArray, of the same size as inArray. The value at nanArray(index) is true when inArray(index) is NaN. Otherwise, the values are false.
allNonzero = all(inArray) - all identifies whether all array elements are non-zero (true). Instead of testing elements along the columns, all(inArray, 2) tests along the rows. all(inArray,1) is equivalent to all(inArray).
anyNonzero = any(inArray) - any identifies whether any array elements are non-zero (true), and false otherwise. Instead of testing elements along the columns, any(inArray, 2) tests along the rows. any(inArray,1) is equivalent to any(inArray).
logicArray = ismember(inArraySet,areElementsMember) - ismember returns a logical array logicArray the same size as inArraySet. The values at logicArray(i) are true where the elements of the first array inArraySet are found in the second array areElementsMember. Otherwise, the values are false. Similar values found by ismember can be extracted with inArraySet(logicArray).
any(x) - Returns true if x is nonzero; otherwise, returns false.
isnan(x) - Returns true if x is NaN (Not-a-Number); otherwise, returns false.
isfinite(x) - Returns true if x is finite; otherwise, returns false. Ex: isfinite(Inf) is false, and isfinite(10) is true.
isinf(x) - Returns true if x is +Inf or -Inf; otherwise, returns false.

Relational Operators

a < b - a is less than b

a > b - a is greater than b

a <= b - a is less than or equal to b

a >= b - a is greater than or equal to b

a == b - a is equal to b

a ~= b - a is not equal to b

a & b, and(a, b)

a | b, or(a, b)

~a, not(a)

xor(a, b)

fctName = @(arglist) expression - anonymous function
nargin - keyword returns the number of input arguments passed to the function.

Looping

while condition

% code

end

for index = startVal:endVal

% code

end

continue: Skips the rest of the current loop iteration and begins the next iteration.
break: Exits a loop before it has finished all iterations.

switch expression

case value1

% code

case value2

% code

otherwise

% code

end

Comprehensive Overview (may repeat)

Built in functions/constants

abs(x) - absolute value

pi - 3.1415...

inf - ∞

eps - floating point accuracy 1e6 106

sum(x) - sums elements in x

cumsum(x) - Cumulative sum

prod - Product of array elements cumprod(x) cumulative product

diff - Difference of elements round/ceil/fix/floor Standard functions..

*Standard functions: sqrt, log, exp, max, min, Bessel *Factorial(x) is only precise for x < 21

Variable Generation

j:k - row vector

j:i:k - row vector incrementing by i

linspace(a,b,n) - n points linearly spaced and including a and b

NaN(a,b) - axb matrix of NaN values

ones(a,b) - axb matrix with all 1 values

zeros(a,b) - axb matrix with all 0 values

meshgrid(x,y) - 2d grid of x and y vectors

global x

Ch. 11 - Custom Functions

function [ outputArgs ] = MainFunctionName (inputArgs)

% statements go here

end

function [ outputArgs ] = LocalFunctionName (inputArgs)

% statements go here

end

You are allowed to have nested functions in MATLAB

Anonymous Function:

fctName = @(argList) expression
Ex: RaisedCos = @(angle) (cosd(angle))^2;

global variables - can be accessed from anywhere in the file
Persistent variables
persistent variable - only known to function where it was declared, maintains value between calls to function.

Recursion - base case, decreasing case, ending case
nargin - evaluates to the number of arguments the function was called with

Ch. 12 - Plotting

plot(xArray, yArray)
refer to help plot for more extensive documentation, chapter 12 only briefly covers plotting

plot - Line plot

yyaxis - Enables plotting with y-axes on both left and right sides

loglog - Line plot with logarithmic x and y axes

semilogy - Line plot with linear x and logarithmic y axes

semilogx - Line plot with logarithmic x and linear y axes

stairs - Stairstep graph

axis - sets the aspect ratio of x and y axes, ticks etc.

grid - adds a grid to the plot

gtext - allows positioning of text with the mouse

text - allows placing text at specified coordinates of the plot

xlabel labels the x-axis

ylabel labels the y-axis

title sets the graph title

figure(n) makes figure number n the current figure

hold on allows multiple plots to be superimposed on the same axes

hold off releases hold on current plot and allows a new graph to be drawn

close(n) closes figure number n

subplot(a, b, c) creates an a x b matrix of plots with c the current figure

orient specifies the orientation of a figure

Animated plot example:

for j = 1:360

pause(0.02)

plot3(x(j),y(j),z(j),'O')

axis([minx maxx miny maxy minz maxz]);

hold on;

end

Ch. 13 - Strings

stringArray = string(inputArray) - converts the input array inputArray to a string array

number = strLength(stringIn) - returns the number of characters in the input string

stringArray = strings(n, m) - returns an n-by-m array of strings with no characters,

doing strings(sz) returns an array of strings with no characters, where sz defines the size.

charVec1 = char(stringScalar) char(stringScalar) converts the string scalar stringScalar into a character vector charVec1.

charVec2 = char(numericArray) char(numericArray) converts the numeric array numericArray into a character vector charVec2 corresponding to the Unicode transformation format 16 (UTF-16) code.

stringOut = string1 + string2 - combines the text in both strings

stringOut = join(textSrray) - consecutive elements of array joined, placing a space character between them.

stringOut = blanks(n) - creates a string of n blank characters

stringOut = strcar(string1, string2) - horizontally concatenates strings in arrays.

sprintf(formatSpec, number) - for printing out strings

strExp = sprintf("%0.6e", pi)

stringArrayOur = compose(formatSpec, arrayIn) - formats data in arrayIn.

lower(string) - converts to lowercase

upper(string) - converts to uppercase

num2str(inputArray, precision) - returns a character vector with the maximum number of digits specified by precision

mat2str(inputMat, precision), converts matrix into a character vector.

numberOut = sscanf(inputText, format) - convert inputText according to format specifier

str2double(inputText)

str2num(inputChar)

strcmp(string1, string2)

strcmpi(string1, string2) - case-insensitive comparison

strncmp(str1, str2, n) - first n characters

strncmpi(str1, str2, n) - case-insensitive comparison of first n characters.

isstring(string) - logical output

isStringScalar(string) - logical output

ischar(inputVar) - logical output

iscellstr(inputVar) - logical output.

isstrprop(stringIn, categoryString) - returns a logical array of the same size as stringIn, with true at indices where elements of the stringIn belong to specified category:

iskeyword(stringIn) - returns true if string is a keyword in the matlab language

isletter(charVecIn)

isspace(charVecIn)

ischar(charVecIn)

contains(string1, testPattern) - boolean outputs if string contains a specific pattern

startsWith(string1, testPattern) - also logical output

endsWith(string1, testPattern) - also logical output

strfind(stringIn, pattern) - returns INDEX of each occurence in array

number = count(stringIn, patternSeek) - returns the number of occurences of string scalar in the string scalar stringIn.

strip(strArray) - removes all consecutive whitespace characters from begining and end of each string in Array, with side argument 'left', 'right', 'both'.

pad(stringIn) - pad with whitespace characters, can also specify where.

replace(stringIn, oldStr, newStr) - replaces all occurrences of oldStr in string array stringIn with newStr.

replaceBetween(strIn, startStr, endStr, newStr)

strrep(origStr, oldSubsr, newSubstr) - searches original string for substric, and if found, replace with new substric.

insertAfter(stringIn, startStr, newStr) - insert a new string afte the substring specified by startStr.

insertBefore(stringIn, endPos, newStr)

extractAfter(stringIn, startStr)

extractBefore(stringIn, startPos)

split(stringIn, delimiter) - divides string at whitespace characters.

splitlines(stringIn, delimiter)

cheat-sheet

Adam Danz
最後のアクティビティ: 2024 年 10 月 30 日

Find unsuppressed outputs in R2024b using dbstop

It's frustrating when a long function or script runs and prints unexpected outputs to the command window. The line producing those outputs can be difficult to find.

Starting in R2024b, use dbstop to find the line with unsuppressed outputs!

Run this line of code before running the script or function. Execution will pause when the line is hit and the file will open to that line. Outputs that are intentionaly displayed by functions such as disp() or fprintf() will be ignored.

dbstop if unsuppressed output

To turn this off,

dbclear if unsuppressed output

Kaustubh / Can It Run Doom?

Chen Lin
最後のアクティビティ: 2024 年 10 月 30 日

Week 3 Winners Announced! Final Week to Submit Entries

We are thrilled to see the incredible short movies created during Week 3. The bar has been set exceptionally high! This week, we invited our Community Advisory Board (CAB) members to select winners. Here are their picks:

Mini Hack Winners - Week 3

Game:

Sandeep T / Sometimes you gotta run, before you can walk

Holidays:

Vasilis Bellos / Floating Pumpkins

Zhaoxu Liu / slandarer / XMas tree1

Fractals:

Greg Hungerford / Distorted Newton's Method Fractal I

Realism:

Jenny Bosten / The Mathworks nebula in flux

Great Remixes:

Timothy / Yurgen

Jr / 2/2 - Sunset

Seamless loop:

William Dean / Bouncy Ball

Fun:

Dhimas Mahardika / Love Wave Function

KARUPPASAMYPANDIYAN M / Olympic Race 2036: India's Dream

Weekly Special Prizes

Vasilis Bellos / Creating seamless loop animations by zooming in

Special shoutout to @Vasilis Bellos. This article was featured on the MATLAB Blog.

Teodo / Schwarzschild Radius: The Edge of Darkness

Thank you for sharing your tips & tricks with the community. You won a limited-edition MATLAB Shorts.

We still have plenty of MATLAB Shorts available, so be sure to create your posts before the contest ends. Don't miss out on the opportunity to showcase your creativity!