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Alan Stevens


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386 total contributions since 2020

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Answered
non linear implicit equation
Surprisingly, this has an explicit solution for y (I didn't use Matlab to get it as I don't have the symbolic toolbox to hand) ....

9 hours ago | 0

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How to write the codes for this gamma function?
Compare your coded value of 154056.7 with the equation's value of 154.056.

11 hours ago | 0

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Poisson Boltzmann eq. with an infinite boundary condition
I suspect the initial gradient required to get zero at infinity is an irrational number (or possibly a rational number with a la...

11 hours ago | 0

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How to solve s system of coupled nonlinear ODES already given the state vector
You need to solve for all xdots simultaneously - this is done in matrix format below. There were also a number of errors in you...

15 hours ago | 1

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How to round UP to 1 decimal value?
ceil(x*10)/10

16 hours ago | 0

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Generate and Plot N Points Picking Random Points on Triangle
More like the following; rng('shuffle'); n = 1000; % Set number of points as desired % Let (0,0) be vertex 1, (0,2) be verte...

1 day ago | 0

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Finding the streamlines of a complex potential for a Joukowsky transform from a unit circle to a flat plate.
x=0:. There was a strange vertical line that O thought was related to this. However, you could put it back and see if it makes a...

1 day ago | 1

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Finding the streamlines of a complex potential for a Joukowsky transform from a unit circle to a flat plate.
There are some typos in the paper by Smith et al, and some steps left out. I think the following generates figure 18: x = [-2:...

1 day ago | 1

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Answered
How to do write the codes for this summation problem?
Having defined n and T then B = 1./(log(T) - mean(log(T))); Note that in Matlab, log is log to base e.

1 day ago | 0

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how to graph this system of questions into mathlab
You can define the function as follows f = @(v) (-0.001778*v.^2+0.05333*v).*(v<30); The (v<30) part simply multiplies the rest...

1 day ago | 0

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Initialize values at time = 0
You probably want to replace if (lambda(:,1) == lambda(1,1)) & (lambda(:,2) == lambda(1,2)) by if (lambda(r,1) == lambda(1,1)...

1 day ago | 0

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ode arguments error in function
For the last line in your function you need dYfuncvecdW = [dXdW; dydW]; Notice the semicolon after dXdW Also your plot comman...

2 days ago | 0

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How do I solve Time dependent parameter in ODE
Perhaps your code needs to be structured more along the following lines; tspan = ..... y0 = ..... options = ..... [t, ymod...

3 days ago | 0

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How to plot min and max values on graph
If you meant you want to highight all the peaks and troughs then the following will do it (assuming you haven't got the findpeak...

3 days ago | 0

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Plotting a rankine half body
Try this m=3; %strength U = 20;%positive x-axis %Mesh for fourth quadrant and corresponding stream value function [X1,Y1] = ...

4 days ago | 1

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Integration by numerical methods
Something like this: z = 0.01:0.01:1; I = zeros(1,numel(z)); for i = 1:numel(z) I(i) = integral(@(x) sqrt(x)./(exp(x)./z(i) ...

4 days ago | 0

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Can someone help me write out this equation for chi-square please
As long as y, m and err_y have the same number of elements then your expression should work ok.

5 days ago | 0

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How to solve two coupled differential equations using ode45.
The following should help: % tspan = [0 tend]; % IC = [1 0 0]; % initial conditions % [t, X] = ode45(@fn, tspan, IC);...

5 days ago | 0

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Answered
Index in position 2 exceeds array bounds (must not exceed 14).
Odd! It works for me: >> C(1,1)= 1; C(1,10) =-1; C(1,16) = 1; C(2,2) = 1; C(2,10) = 1; C(2,11) =-1; C(3,3) = 1; C(3,11) = 1;...

6 days ago | 0

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how to find a root of polynomial using matlab
Or directly y = sqrt(2)*atan(-1/3);

6 days ago | 0

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How to give input function dz/dt=Z*omega*cos(omega) to state space system?
Do you mean something along these lines: tspan = [0 2]; % Or whatever you need IC = [1 0]; % Set your own initial conditi...

6 days ago | 0

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how can i solve nonliner equation?
look at documentation on the "roots" function, (ie type help roots).

6 days ago | 0

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I am not getting graph for RK4
Looks like you are confusing Y with y.

6 days ago | 0

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How do I solve this bvp4c error ?
You have a division by sinh(k) .../(2*sinh(k)))... Since k is zero, sinh(k) is zero and the resuting expression for vel is NaN...

7 days ago | 0

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Answered
Simulate a 2-input linear system with with ode45
More like this: tspan = [0 50]; x0 = [0; 0; 0]; u = [10; 10]; [t,x] = ode45(@(t,x) odefun(t,x,u),tspan,x0); x = x'; My = [...

7 days ago | 0

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How to extract non complex number from an array?
A(imag(A)==0)

7 days ago | 0

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Adding Labels to PDE Graph
One way is to do the following with your plot command: plot(x,sol); lg1 = ['t = ',num2str(t(1))]; lg2 = ['t = ',num2str(t(2)...

7 days ago | 0

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Answered
How can I get values for n=500, 1000 and 2000 ? only getting values for n=4000!
Your assignments T.Euler_1(p) = abs(init_cond(1) - z(end,1)); etc. are all outside of the for p = ... loop, hence they just re...

7 days ago | 1

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Answered
why this error ??
You have defined x as a 1x25 vector, but you are calling it with two arguments. You need to call it with x(n), rather than x(1,n...

7 days ago | 0

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How to find x-values when y-function equals a set value?
With your particular function you can get both values of x immediately from x = b1 + c1*sqrt(log(a1/0.7))*[1, -1];

7 days ago | 0

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