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I am trying to code a solution to blasius eq using Runge kutta 4, help please.
clear all; clc; % 3 First order ODE´S from Blasius Eq % dF/deta = G % dG/deta = H % dH/deta = -0.5*F*H fF=@(eta,F,G,H) ...

3 years ago | 0

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How to determine the absolute value of a complex exponential function containing a symbolic variable?
syms omega t real syms I0 positive I = I0*exp(1i*omega*t); abs(I)

3 years ago | 0

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Second degree differential equation
The example Solve Nonstiff Equation under https://de.mathworks.com/help/matlab/ref/ode45.html explains in detail how to proc...

3 years ago | 1

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Unable to perform assignment because the size of the left side is 1800-by-1 and the size of the right side is 4872-by-1.
Anything unclear about the error message ? rxBits has only 1800 rows, but qamdemod(rcomb, 2^bitsinreceiver, 'OutputType', '...

3 years ago | 0

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3D cylinder code debugging
zSC_lid is an 1 x nNodes vector: zSC_lid = repmat([0, hSC], 1, nNodes); Thus it has only one row. But you reference the secon...

3 years ago | 1

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Different output for find(X) and find(X<5)
find(X) lists the array elements of the double array X that are not equal 0. find(X>0) lists the array elements of the logical ...

3 years ago | 1

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the code print -inf in TT matrix. Please anyone helps
Your value of 1 for delta_t violates the CFL condition for stability of the explicit Euler scheme. Choose a value that satisfie...

3 years ago | 0

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how to derivate an equation of x and y without taking any variable constant?
You mean assuming y = y(x) ? syms y(x) f = y-x*y-sin(y) == 0; df = diff(f,x)

3 years ago | 1

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How to solve for gamma
format long dbs=5.3e-10; das=1.01e-9; cb=4e3; ca=1e3; x0 =0; options = optimset('TolX',1e-14,'TolFun',1e-14); x = fsolve(...

3 years ago | 0

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Help solving system of triq equations
%Input Linkage lengths d=11.875; a=2.5; b=11.875; c=3.75; r5=5; r6=6; r7=7; r8=8; L1Theta = zeros(30,4); L1Theta(:,2) ...

3 years ago | 0

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i need to find the displacement for the given values
syms p E = 3*10^4; v = 0.29; a = 39; b = 2*a; d = 1; A = pi/4; I = (pi/64)*d^2; G = E/(2*(1+v)); m =...

3 years ago | 0

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How to initialize number of iteration?
A_100_iteration = cell(51,1); Result_100_iteration = cell(51,1); for ib = 1:51 B(1) = (ib-1)*20; for n = 1:100 ...

3 years ago | 0

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I'm trying to write a matlab function to solve RK4 and store it in my computer to be called when needed.
If you call RK4 correctly, it will work. syms y(x) dy_dx(x) dy_dx(x) = x + y(x); x_1 = 0; y_1 = 1; x_end = 1; h_step = 0.0...

3 years ago | 0

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error: Index in position 2 exceeds array bounds (must not exceed 31).
Note that I had to make changes to the boundary values and your loop ! Compare with your old code to see the errors you made. c...

3 years ago | 0

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function handle as array
M = rand(4,4); P_initial = rand(4,1); P = @(t) mtimes(expm(t.*M),P_initial); P(0) g = @(a,x)a(x); g(P(0),1)

3 years ago | 0

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What does norm function indicate ?
From the MATLAB documentation: n = norm(X) returns the 2-norm or maximum singular value of matrix X, which is approximately max...

3 years ago | 0

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My code is giving me a straight line for values of N other than 5
I'm quite sure that the 0.5 has to be taken out of the symsum: syms k N integer syms t y = 0.5 + symsum((cos(k*pi)-1)*(2/((k*...

3 years ago | 0

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Numerically integrate a time dependent differential equation
bP = 1; Te = 1; K = 1; t0 = 1; ti = 24; CDF = @(x)integral(@(t) 1/t0*exp(-bP./(Te^4+K*(307.59-190.96*(log(t/24)).^0.24)).^0...

3 years ago | 0

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Cant take the derivative of this plot...
m = 1; b = 2; k = 10; tnum = linspace(0,7,175); xlabel('0'); syms s F=1/(m*s^3+b*s^2+k*s); f=ilaplace(F); df=diff(f); v...

3 years ago | 0

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Could you please provide script to perform process described below. Many thanks in advance
A = rand(7) A = A(:,4) writematrix(A, 'A.txt')

3 years ago | 0

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Error message when trying to plot
T = K ./ sqrt(2*pi*w); instead of T=(K/(sqrt(2*pi*w)));

3 years ago | 0

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Multiple boundary conditions with two separate intervals
To use bvp4c, the two intervals have to be connected. Thus in your case, it's not applicable (or only with big effort). syms y1...

3 years ago | 0

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how to plot a periodic function?
a = 3.2; t1 = 5; t2 = 7; t3 = 12; t4 = 17; fun = @(x) a*(x>=0 & x<=t1) + (-a/(t2-t1)*(x-t2)).*(x>t1 & x<=t2) + (-a/(t3-t2)*...

3 years ago | 0

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How can I solve coupled nonlinear hyperbolic equations?
CLAWPACK available under https://www.clawpack.org/ is an excellent solver for hyperbolic systems of differential equations. A...

3 years ago | 0

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How to add integral in a integral function
format long integral(@(x)sin(integral(@(a)sin(a),0,x)),0,1,'ArrayValued',true) integral(@(x)sin(1-cos(x)),0,1)

3 years ago | 0

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why while loop repeats so long?
If you output "count" for the numerical solution, it's about 14000. Now if you measure the time for one symbolic iteration in ...

3 years ago | 0

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vector and for-loop issues in ode solver
%Parameters input.n=10; % # in r input.Ea=63000; % [J/mol] input.R=8.314; % [J/mol/K] input...

3 years ago | 0

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Basis function regression for 3 parameters
Put the equations y(x1(i),x2(j),x3(k)) = a_0*f_0(x1(i), x2(j), x3(k)) + a_1*f_1(x1(i), x2(j), x3(k)) + a_2*f_2(x1(i), x2(j), x3...

3 years ago | 0

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Eigenvalues in symbolic matrix
Replace %% 2.stability analysis J=jacobian([gp(1)*vp(1)./(kp(1)+N0)*N*P1 - mp(1)*P1^2==0, ... gp(2)*vp(2)./(kp(2)...

3 years ago | 0

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sum of Bessel function
m = 0:250; x = linspace(-5*pi,5*pi,1000).'; A = 2./((2*m+1)*pi).*besselj(0,pi/2*m).*sin(1000*(2*m+1).*x-(2*m+1)*pi/2); f = su...

3 years ago | 0