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Alan Stevens


Last seen: Today Active since 2020

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Answered
Solve a system of 3 second order equations
Write your equations as 6 first order equations like so: where I've assumed you have pre-defined omegaout and thetaout as fun...

11 hours ago | 0

Answered
Unable to solve nonlinear equation using fsolve as the message shows No solution found
fminsearch makes a reasonable attempt: F1 = @(a,b) -9.135789053E+00-log(a)+166.2509975*a+5.84074229*b+... -166.2509975*a^2...

1 day ago | 2

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How to solve and plot this set of differential equations?
If rho starts at 0, then drho/dtheta will be zero and rho will not change from zero according to your first ode. If rho and drh...

3 days ago | 0

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How can I add two differential equations to the system in a given time interval?
Like this? (though I'm not sure I've interpreted which constants apply during which interval correctly!) Tspan = 0:30; C0 =...

7 days ago | 1

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Answered
How do I plot Rosette-like diagram in this case?
Something like this? data=[10 10 30 100; 20 50 70 150; 30 45 60 120]; theta0 = deg2rad(data(:,2)); thetaf = deg2r...

8 days ago | 1

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Answered
Iteration of multiple nonlinear functions
Here's a quick and dirty way. I'll leave you to modify the following to record all the temperatures at every step. %Given valu...

19 days ago | 0

Answered
converting table values to RPM
B{:,7}./(2*pi)*60

21 days ago | 0

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using num2str for subplot titles
Try title(['Q1S', num2str(k)]) i.e. enclose the two terms within square brackets.

21 days ago | 0

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Answered
control and simulation of petroleum distillation column
The following works, but probably doesn't contain all the right data or equations! % CALCULATE MATERIAL BALANCES FOR THE DISTIL...

22 days ago | 0

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Answered
Error with plot command
You haven't specified function atten_func_dist, so we can't run your code to test it. You specify fre as a constant, then us...

23 days ago | 2

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Answered
How to combine multiple curve fits in one plot
Use hold on after plotting the first figure

25 days ago | 0

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How to represent [airfoil] coordinates as a polynomial
How about using a spline fit? After loading your data and calling the first column x and the second column y try xfit = linspa...

27 days ago | 0

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1D melting problem with Neumann's analytical solution
eps is a built-in constant so better not to use it as a variable. Your png files show it is xi not epsilon. Try the following ...

27 days ago | 0

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Answered
Overlay plots of different angles of incidence.
Remove the word figure and add hold on after the plot grid on [Fr,In] = meshgrid(Frequency,Incident); plot3(Fr,In,Reflectivit...

28 days ago | 0

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How can write in MATLAB the following expression?
Try ket0 = [1; 0; 0] ket1 = [0; 1; 0]

1 month ago | 0

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Answered
I don't understand why does it give error?
Put the functions at the end. Tidy up one or two minor errors to get: %########### BF-PSO.m file ############# %####### Butter...

1 month ago | 0

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How to count steps represented by the acceleration data given in text file?
Like this (you can plot the other two - look up help on subplot): M = csvread('walking.txt'); x = M(:,1); y = M(:,2); z = M(:,...

1 month ago | 0

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Answered
Bisection method add iteration table into my code
Something like this? my_fun = @(x) exp(x) - 3*x; low = 0; high = 1; tolerance = .00001; [x, x0] = bisection(my_fun, low, hi...

1 month ago | 0

Answered
I'm trying to solve this code for internal ballistic using ode45.This is my first time using ode
This works (note that Matlab doesn't accept implied multiplication), but doesn't look sensible - what about deriv(2)? y_initial...

2 months ago | 0

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Answered
Error with brackets symsum
Do you mean something more like this? N = 100; % Total number of particles one = 1; alpha = 1; K = 7; % 7 states n0 = 4*o...

2 months ago | 0

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How to plot the figure in LT?
Use the mod function help mod

2 months ago | 0

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How to deal with rounding error in this example?
How about i = 1:20001; A = -2000 + (i-1)*0.2;

2 months ago | 1

Answered
Get back variables out of function inside a for loop
Here's one way J = [2.5 27 56]; WZ = [12.2 23.2 33]; M1 = 22; I1 = 2600; for ii = 1:numel(WZ) slope(ii) = (J(ii)-M1)...

2 months ago | 1

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Answered
Plot dispersion curves using Bloch theorem
Like this? OmegaR = 1; mR = 0.125; Omega = 0:0.01:2.5; mu = acos(1 - Omega.^2.*(1+mR./(1-Omega.^2/OmegaR^2))/2); plot(i...

2 months ago | 0

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Answered
how to do sensitivity analysis of three variables using MATLAB
Depends what your measure of sensitivity is. One possibility is to do a Monte-Carlo simulation and use the standard error on th...

2 months ago | 0

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Answered
MATLAB doesn't plot my function
Try fplot(test1)

2 months ago | 0

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Answered
I am trying to plot the each value of C at different theta values, but I found an error. Error: Invalid expression. When calling a function or indexing a variable, use parenth
Do you want something more along the following lines? c=[0.5,0.75,1,1.1]; theta=-pi:0.01:pi; %a=zeros(1,629); for k=1:numel(...

2 months ago | 0

Answered
Trying to make euler's method program work
Like this: % Arbitrary values here - insert your own x0 = 0; x_end = 10; h = 0.1; y0 = 1; n = fix((x_end-x0)/h)+1; ...

2 months ago | 0

Answered
Why does integration of an exponential function generate noisy results as opposed to its analytical solution?
You have a singularity when t = x(ii). Here's a rough and ready way to do the numerical integral (hmm! not sure the result is c...

2 months ago | 0

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