Community Profile # Alan Stevens

Last seen: Today 2020 以来アクティブ

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Why is my loop not ending?
Shouldn't dp(i+1)= ((6*m(i+1))/(pi*row))^(1/3); be dp(i+1)= -((6*m(i+1))/(pi*row))^(1/3); i.e. have a negative sign in front...

3日 前 | 0

Explicit solution can not be found using dsolve of second order differential equation
Do you have a reason to believe there is an analytical solution to this? It is simply solved numerically, as follows: X0 = [1,...

15日 前 | 0

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i am trying to add a legend for the 0.2% offset line onto the graph, but when i run this, the previous three legend just disappear.
Just put '0.2 offset line' as a fourth item in your other legend command.

15日 前 | 0

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Minimizing an equation to 0
Try fminsearch

15日 前 | 0

Solving for two variable.
In that case one way is to take logs of both sides to get: log(I) = log(I0) + q/(n*k*T)*U then do a best-fit straight line...

16日 前 | 0

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I couldn't plot the function because it seems vector length isn't same, please help me in it.
Try changing n = 100 for i = 1:n to n = numel(time); for i = 1:n-1

18日 前 | 0

How to plot an array graph from a 'for' loop?
Try multiplying i by delta_t in the plot command x(1) = 1; delta_t = 0.1; n = 100; for i = 1:n hold on grid ...

19日 前 | 1

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Display text label on top of grouped bar plots

19日 前 | 0

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Solving coupled second order differential equations
Something like this? m1 = 10; m2 = 20; c = 30; k = 5; tspan = [0 1]; ic = [...

20日 前 | 0

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How to create an objective function c(t) to use fminserch , struggle with the summatoin , i used the following code for the optimization but it doesn't seem to work
Do you mean something like this: KT0 = [1, 10]; % initial guesses [KT, C] = fminsearch(@FN, KT0); K = KT(1); T = KT(2); d...

27日 前 | 1

Generate diagram in linear scale
See help polyval

27日 前 | 0

error bar on group plot :X-data must be the same size as Y-data.
Something like this? % Set up the problem by recreating the table. A = [ 0 0 1 1 2 2 3 3]'; B = ['0' '1' '0' '1' '0' '1' '0' ...

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Improving fit of data to sum of cosines model
Try changing the dihedral angles to radians (or change cos to cosd in expr).

Solving 2d laplace equation with insulation ,,,,, code won't work because the error doesn't get below 1 neeeed help
Like this? m=7; n=9; L=40; H=30; dx=L/(n-1); dy=H/(m-1); x=0:dx:L; y=0:dy:H; lamda=1.5; epsilon=1e-4; %% T=zero...

I want to do stop condition which demand dx=0 in coupled differential equations
You could do something like the following (doesn't actually stop the integration, but only plots the relevant bit): alpha=0.5; ...

Energy balance of stirred tank
Try doc ode45

Increasing number of data points by linear interpolation method
Try doc interp1

I have two 4x4 matrices. I sub-divided these matrices in 4 2x2 matrices each. Now I want to compare these 2x2 matrices.
Something like this: M1 = [8 7 6 9; 11 13 4 21; 2 69 33 27; 5 3 1 8]; M2 = [0 1 0 1; 1 0 1 0; 0 1 0 1; 1 0 1 0]; M = M1.*M2...

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Solving inter-connected ODE equations
The answer is Yes. You have a system of 9 ODE's. Try help ode45 for details on how to do it.

support vector regression - Coefficient of Determination
Have a look at: https://uk.mathworks.com/matlabcentral/fileexchange/34492-r-square-the-coefficient-of-determination?s_tid=srcht...

Value of infinite integral is different
The value of your integral is infinite! Are you sure you have written the function S correctly?

Evaluating the following integral using comp trap method for 2 trapezoids
You need to divide by the true value of the integral in calculating the error: y = @(x) (10 - 2*cos(x)); b= pi/3; a = 0; ...

How to Use Nested For Loops to Create a Coupled System of Equations
More like this perhaps (you've very tight tolerances!): options = odeset('RelTol',3e-14,'AbsTol',1e-15,'Stats','on'); [t,y]=od...

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Solving Trigonometric Equations with More Than One Variables
You have theta = 30degrees, so sin(theta) is 1/2. Therefore, in equation 2, you have cos(psi)/2 = 0.76, so cos(psi) > 1. If ...

Plot 2D surf from 3 columns (X, Y, Data)
plot3 will plot your points as a line (or series of points). To get a surface, set up regular coordinates over the appropriat...

I want to plot v/vth as a function of y(where y varies from [0 d] and d=6)
The integral is infinite if you let phi go all the way to phim. If you restrict the upper limit of the integral to be less than...

2ヶ月 前 | 1

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4th order runge-kutta method to solve two 1st order differential equations
Like this? %%4th order runge-kutta for Project 2 fy=@(t,y,z) z; fz=@(t,y,z) (36000/(1500-40*t))-9.81-((0.1962*z^2)/(1500-40*t...

3ヶ月 前 | 0

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How to convert this equation to code?
Use ^ not **

3ヶ月 前 | 1

need help with mass transfer modelling
Here's one way of doing it: % You need to do the time integration for each C separately C = 150:50:250; % Choose your own ...

3ヶ月 前 | 1

Function of a variable
You need to define sc before using it in B. In B you have ...1000/dref*dref.... This just means the dref va;lues cancel each ...

3ヶ月 前 | 0