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terminate loop diverging to inf
I'm not sure, but I guess you meant something like this: NT = 1024; N = 2048; r = 0.9; omega = (sqrt(5)+1)/2; phi = 2*pi*om...

2年以上前 | 0

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Sum of sines optimized starting points
https://uk.mathworks.com/matlabcentral/answers/511413-curve-fitting-tool-starting-points If your problem is linear in the fitti...

2年以上前 | 0

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My index starts at the second element. I dont know why
Before MATLAB enters the for-loop, t(i), v(i) and x(i) are only defined for i = 1. In the loop, you also don't define t(i), v(i)...

2年以上前 | 0

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Rational function produced by the Curve Fitter App does not match the output graph
Look up the documentation to see what the option opts.Normalize = 'on'; means. The coefficients are used to approximate y vs...

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Badly conditioned equations - how can I centre and scale properly
Your problem is linear, but fitting data with an independent coordinate up to 1500 by a polynomial of degree 12 is nonsense. al...

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Unable to perform assignment because the left and right sides have a different number of elements.
k1v and k2v both are vectors of size 1x60001, but they must be scalars in the assignment. Maybe you mean V(j+1) = V(j) + (k1v(...

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How can I simplify this expression using "abs" function?
You must determine the value for k0 where the expression 2*n^3 + 3*n^2 + n - 2*k^3 - 3*k^2 - k - k*(k+1)*(2*k+1) changes sign ...

2年以上前 | 0

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PDEPE function - BCFUN error
Use function [ptop, qtop, pbot, qbot] = bcfun(ztop, Ttop, zbot, Tbot,t) % hc and Hs are vectors ptop = hc.*(Ttop-env(:,1))+ e...

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I need help with elemental wise operation for a first point iteration method
%% Input Variable Uinf = 11; % freestream veloctiy (m/s) R = 6.25; % Radius of Rotor (m) ...

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Solve ODE without initial condition
Your ODE is nonlinear. The symbolic toolbox is not able to find an analytical solution for it. You will only be able to solve it...

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this is my sample code and i have to plot 8 by 8 matrix in my actual code, the code itself is correct but it is taking forever,any other way to plot this please help
w=1:3; c44 = 44; n = numel(w); y = zeros(n,1); y1 = zeros(n,1); y2 = zeros(n,1); y3 = zeros(n,1); for j = 1:numel(w) y...

2年以上前 | 0

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ODE45 solving 3 equations and comparing to RK-4
%% RK4 methods %% Description % RK4 methods are used to solve coupled first-order ODEs clear close all clc %% Input vari...

2年以上前 | 0

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How to check the convergence and accuracy of the Problem using BVP4c
Inf = 3 seems to be sufficient: global alpha beta Pr Nb Nt %eq1 alpha=1.2; beta=0.3; %eq2 Pr=1.7; Nb=0.1; Nt=0.1; hold o...

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How can I plot?
syms b omega r t theta T delta b = 0.1; omega = 2*pi/5; r = b*(1+omega*t); theta = omega*t; C = [r*cos(theta); r*sin(theta)];...

2年以上前 | 0

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why isn't my newton rhapson method giving me a quadratic conversion rate?
If b=log(d/dI)/(2*kw); instead of b=log(d/dI)/2*kw; as was first written in your previous code, then B must also be B=(log(...

2年以上前 | 0

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I am getting this error "Index exceeds the number of array elements. Index must not exceed 1."
You define ICs = 43.4; Therefore, ode15s expects that you want to solve one differential equation. Consequently, "var" in th...

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While loop shows the result of the previous run
% Check if there's any change in the matrix positions previous_matrix = matrix; % Store the previous matrix ...

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Run pdepe solver in adjacent domains: introduce flux BC at the interface
If you make r = R_T a point of the r-vector, the finite element solver pdepe will automatically respect continuity of c and dc/d...

2年以上前 | 0

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Derivative not working plot
clear; clc; close all; % Curve Fit x = [6500 6350 6000 5400 5200 4500]; y = [0 0.25 0.5 0.75 0.875 1.0]; theFit=fit(x'...

2年以上前 | 0

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while loop running forever during attempt at Newton Rhapson method
Your function doesn't seem to have a zero. d=0.007; dI=1.219; Rfi=1.76*(10^(-4)); Rf0=Rfi; hs=356; ht=hs; kw=60; dTm=29....

2年以上前 | 0

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For loop doesn't work well.
Somewhere in the line P(i) = P(i-1) - dPD_tot(i); the "dx" must come into play because you usually compute the pressure gradie...

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I have a problem with the convergence of fsolve ?
You could try solution = [10,10,1.2]; % Initial guess for R1, R2, Omega % Solve the equations for eachU value for i = 1:lengt...

2年以上前 | 1

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How manage for loop to calculate distances?
I should have a new "all_distances" variable with 5 values of distance, but it is only showing the error: Why 5 ? You should ha...

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runge kutta algae flower
Don't you have to call rk4 twice for stepsize h/2 to compare the results ? And shouldn't the Runge-Kutta step be pout = xk + (...

2年以上前 | 0

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Find all possible combinations of numbers with a specific array length
M = categorical(["A","B","C","D"]); combinations(M,M,M,M,M,M,M,M,M,M,M,M)

2年以上前 | 1

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Finite method for a heat generating furnace
You use "j" twice as loop index in a nested loop. This will give problems. for j=1:Ny for i=1:Nx if i==Nx...

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Not enough input arguments. Error in mypde_model>bcfun (line 53) ptop =utop - interp1(time, mydata(:,5), t,'spline'); Error in mypde_model (line 17) sol = pdepe(m, @pdefun,
Use sol = pdepe(m, @pdefun, @(z)icfun(z,u_ini1,u_ini2, Z),@(ztop, utop, zbot, ubot,t) bcfun(ztop, utop, zbot, ubot,t,time, myda...

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Unable to find explicit solution.
You must use "dsolve", not "solve": syms t x(t) K eqn = diff(x,t) == (1-x/K)*x; dsolve(eqn)

2年以上前 | 1

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Doubt in Coupled Ode
Your code is correct, but it seems there is a singularity near 0.32.... syms t x(t) y(t) a1 b1 a2 b2 Constant eqn1 = diff(x,t,...

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Solving a complex system of differential equations
%q(1) = X, q(2) = Y, q(3) = Xdot, q(4) = Ydot M = [1,0.8;0.8,7]; K = [5,0;0,10]; D = [0.15,0;0,0.35]; F = @(t)[5*exp(i*5*t);...

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