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Simplify symbolic division abs(Z)/Z
Use z*z' instead of abs(z)^2: syms z u = z*z'/z

mehr als 2 Jahre vor | 0

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Why is ode45 failing to solve this system of ODEs?
Your matrix L has 9162 NaN values. This is most probably caused by the division by (x+1) which is problematic for the problem b...

mehr als 2 Jahre vor | 1

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Store Values in Array per Loop iteration issues
Replace [i, ~] = find(Strain < 0.01 | Strain > 0.15); Strain(i, :) = []; by [j, ~] = find(Strain < 0.01 | Strain > 0.15); S...

mehr als 2 Jahre vor | 0

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I need to pursue the developement of a variable within a function, but I don't know how.
[t_num,x_num]=ode15s(@DGL,tspan,q0); C11_num = c_m+c_a*sin(om*x_num(:,1));

mehr als 2 Jahre vor | 1

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Im trying you solve the component mass balance and energy balance equations for an adsorption system. Im getting some exponential growth in the plots.
Use Upwind Differencing for the convection terms: dTdz(2:n) = (T(2:n)-T(1:n-1))/h; dJdz(2:n) = (J(2:n)-J(1:n-1))/h...

mehr als 2 Jahre vor | 0

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Error using bvp4c Unable to solve the collocation equations -- a singular Jacobian encountered. Error in MHDI_ori (line 54) sol = bvp4c (@OdeBVP, @OdeBC, solinit, options
You say you want to have yb(2) - R = 0 and yb(2) - 1 = 0 at the same time as boundary conditions. This is not possible.

mehr als 2 Jahre vor | 1

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Error with 3D interpolation: Interpolation requires at least two sample points for each grid dimension
VsGrid = csvread('3d_Vs_utm_samplefile.csv'); X = VsGrid(:,1); % UTM X Y = VsGrid(:,2); % UTM Y Z = VsGrid(:,3); % Depth V =...

mehr als 2 Jahre vor | 0

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Where to find Hash Sums of Matlab Downloads?
Does this help ? https://codesigningstore.com/how-to-check-file-checksum https://uk.mathworks.com/matlabcentral/answers/540626...

mehr als 2 Jahre vor | 0

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How do I generate a random number vector composed of just 1 and -1
s = -1 + 2*randi([0 1],100,1) nnz(s==-1) 100-nnz(s==-1)

mehr als 2 Jahre vor | 1

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How can I plot graph in this relationship?
s=0; hold on for j=1:1:10 s=s+j; disp(['j = ', num2str(j)] ); disp(['s = ', num2str(s)] ); plot(j,s,...

mehr als 2 Jahre vor | 0

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Array Problem How can I unpack an array? why the firt element pf my array is always 0?
We don't know how you call the function - so we cannot predict I1, I2 and I3. To your second question: I = [3 5 -6]; [I1,I2,I...

mehr als 2 Jahre vor | 0

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Integrate pressure over area, from dataset points
Maybe you want to get mean pressure over the face. In this case, divide "sol" by area = pi*(5^2-1^2) as done below. x = load("x...

mehr als 2 Jahre vor | 1

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Why do I have an error with minus sign
There is a minus sign in front of d^2M/dx^2 which is difficult to see. So everything is ok: f_0*(x/L)*(1-(x/L)) = -(f_0*x*((x/L...

mehr als 2 Jahre vor | 1

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Out of memory - dsolve 3rd order system
Does this one work better ? syms t y1(t) y2(t) y3(t) f = 10*exp(-t); eqn1 = diff(y1) == y2; eqn2 = diff(y2) == y3; eqn3 = d...

mehr als 2 Jahre vor | 0

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Solve these unkowns x and y using these 2 simultaneous equations
I think you want to use sind and cosd instead of sin and cos. This is a linear system of equations in m3R3L3 and m4R4L4. You kn...

mehr als 2 Jahre vor | 0

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How do I include or make a discrete variable for an optimization problrm?
Make a loop over the 4*4*3*3 = 144 possible combinations of x1,x2,x3 and x4 and only optimize with respect to x5, x6 and x7. In...

mehr als 2 Jahre vor | 0

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I want to solve these 2 simultaneous equations to get x and y
syms x y equ1 = 73*sind(0)+92*sind(200)+87*sind(x)+65*sind(y) == 0; equ2 = 73*cosd(0)+92*cosd(200)+87*cosd(x)+65*cosd(y) == ...

mehr als 2 Jahre vor | 0

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i was calculate using gauss jacobi method with 4x4 matrice, why does NaN appear? what should i do?
A(2,2) equals 0, but you divide by 0. What is H ? clc; A=[1 3 1 -1; 2 0 1 1; 0 -1 4 1; 0 1 1 -5]; A=[A(2,:);A(1,...

mehr als 2 Jahre vor | 0

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Index in position 2 exceeds array bounds (must not exceed 25).
Without seeing your data, I'd speculate that spec001 has only 25 columns, but that you try to address columns up to the index 20...

mehr als 2 Jahre vor | 0

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Problem with time plot from partial derivative equation solved by method of lines
It's "Conversion", not "Convertion". And setting a boundary condition at z = L is incorrect because you only have convection, n...

mehr als 2 Jahre vor | 0

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How do I define piecewise constant function in for loop?
Give the correct values to the arrays "left_limit_of_ith_interval" and "right_limit_of_ith_interval" in the following code: lef...

mehr als 2 Jahre vor | 2

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Runge-Kutta 4th Order on a 2nd Order ODE
Comparing with a MATLAB integrator, the results look ok. I don't know how you derived that "the value of k11 shoud be -0.06 bu...

mehr als 2 Jahre vor | 0

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Changing ode solver tolerances on the fly
Is it possible to change (relax) the values of the "Absolute tolerance", Relative Tolerance" on the fly just for the "problem" t...

mehr als 2 Jahre vor | 1

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Saving of state just before nonconvergence of ode solvers
The stepsize before the solver exists usually becomes small. So if you choose "tspan" in the call to the ode integrator as a 2-e...

mehr als 2 Jahre vor | 0

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ODE45 not producing outputs test does not finish
Use a stiff integrator, namely ode15s instead of ode45.

mehr als 2 Jahre vor | 0

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Unrecognized function error in bvp4c (in boundary conditions)
A = 2; B = 1.5; g = load('gr_in.mat'); gr = g.gr; rc = gr(:,2); figure(1) plot(gr(:,2),gr(:,1)) N = 100; r = linspace(rc...

mehr als 2 Jahre vor | 1

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Write function for complicated recurrence relation.
I modified your formula slightly, and after this modification, it seems to give correct results: N = 14; L = zeros(N); L(1,1:...

mehr als 2 Jahre vor | 0

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Fit ellipsoid to (x,y,z) data
https://uk.mathworks.com/matlabcentral/answers/2038016-how-to-plot-the-best-fitted-ellipse-or-circle?s_tid=srchtitle https://uk...

mehr als 2 Jahre vor | 2

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script no longer works after update to 2023b (related to ode45)
Why do you use ode45 for a boundary value problem ? Use bvp4c instead. The below code doesn't give errors or warnings - at leas...

mehr als 2 Jahre vor | 0

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how to code this type of objective function (optimization)
Use "fminimax" and read the documentation on how to apply the software also for maximizing the minimum instead of minimizing the...

mehr als 2 Jahre vor | 1