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

3 months ago | 0

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Answered
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...

3 months ago | 1

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Generate diagram in linear scale
See help polyval

3 months ago | 0

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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' ...

3 months ago | 0

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

3 months ago | 0

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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...

3 months ago | 0

Answered
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; ...

3 months ago | 0

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Energy balance of stirred tank
Try doc ode45

3 months ago | 0

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

4 months ago | 0

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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...

4 months ago | 0

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Answered
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.

4 months ago | 0

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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...

4 months ago | 0

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

4 months ago | 0

Answered
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; ...

4 months ago | 0

Answered
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...

4 months ago | 0

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Answered
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 ...

4 months ago | 0

Answered
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...

4 months ago | 1

Answered
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...

5 months ago | 1

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Answered
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...

5 months ago | 0

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

5 months ago | 1

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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 ...

5 months ago | 1

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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 ...

5 months ago | 0

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I have plotted two circles and I want to anything outside of the first circle (unit circle) to not be plotted or excluded.
Here's one way: np = 100000; min = -pi*1000; max = pi*1000; hold on; a = 0; b = 0; z = a + (1j*b); e = linspace(...

5 months ago | 0

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Answered
How to implementation PSO in Matlab?
Have a look at https://uk.mathworks.com/matlabcentral/fileexchange/67804-particle-swarm-optimization-pso-matlab-code-explanation...

5 months ago | 0

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Answered
Getting regression weights from histogram
Something like this perhaps? % Dummy data N = 1000; M = N/40; T = randn(N,1); h = histogram(T,M); W = max(h.Values)-h.Valu...

6 months ago | 0

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Answered
Custom fitting using equation from differential function
You equation has the analytical solution y = (A/B)*(1-exp(-B*t)). Use fminsearch to fit the parameters, or the curve fitting to...

6 months ago | 0

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Using the nodal method in ventilation analysis
Try removing J_inv=inv(J); and replacing (J_inv(i,j)*fP(i)) by J(i,j)\fP(i)

6 months ago | 0

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Answered
Using Euler's method to solve the system of ODEs
Probably easier to keep tabs on what is happening if you simplify as follows: r=2.5; p=2; c=0.1; b=0.1; q=1; k=0.1; h =...

6 months ago | 0

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Error with the SIR Model
Update N at each timestep. Plot I and R on a different scale from S.

6 months ago | 0

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ODE45 returns NaN
t = 0 causes a problem. Try tspan = [0.1 100]; for example.

6 months ago | 0

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