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Alan Stevens


Last seen: 1 day ago Active since 2020

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Answered
Tring to solve for a transcendental equation
You can rearrange the equation as eigen*tan(eigen) = Bi and use fzero as below. However, because of the nature of tan, your res...

1 day ago | 0

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Answered
Question regarding MATLAB code to solve for electron in constant electric and magnetic field
If you are going to use global variables they need to be declared outside the function as well as inside. Your values of q and ...

4 days ago | 0

Answered
Hello, I am trying to plot the transmission coefficient vs energy for the double barrier potential, but I get an error. May I know what I have done wrong here?
See the following V_0 = 0.2800; % Barrier strength in eV hbar = 1.054571596e-34; % Reduced Planck constant m = 5.465629128e-3...

4 days ago | 0

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Simulation of point kinetics reactor equations
There are seven equations if you are using all six delayed neutron groups. You don't give your reactivity, nor the individual b...

11 days ago | 0

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calculating angle between line of best fit and x axis
Take the arctangent of the gradient of the straight line.

11 days ago | 0

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deleting separate zeros from vector
Here's one way (there is probably a slicker way!): A = [ 0 0 1 0 0 0 1 0 1 0 0 1 5 9 8 2 0 3 0 1 0 0 0 ]; ...

12 days ago | 0

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Making a Euler Method script to solve for velocity but am encountering "Array indices must be positive integers or logical values" Error
Try changing your loop to for i=1:numel(t) %%% i loop not t f = (g - (D * p * A * v(i).^2)/(2*m)); %%% v(i) v(i+1) ...

12 days ago | 0

Answered
Error solving for a particular variable from two equations
You could use fzero: TonTc = 0.01:0.01:0.99; a = zeros(1,numel(TonTc)); a0 = 1; % initial giuess for k = 1:numel(a) ...

13 days ago | 0

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Answered
Replacing sym with function handle
Do you mean something like this? phi = pi/3; [nr, wr] = fn(phi); disp(phi) disp(nr(4)+56*3/2) disp(wr(4)) function [nr...

13 days ago | 0

Answered
I'm trying to solve this system of ODE's describing a mechanical spring model.
Might be better to forget about symbolics, treat each 2nd order ode as two first order ode's and do the following: %applied for...

16 days ago | 0

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Solving a first order ODE with Euler backwards method
Your y_true is only valid for t>= 5 (smaller values give imaginary results for y). So, try going from 5 to 8: % y_true = log(t...

16 days ago | 0

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Answered
Need help to create a loop
How about: e=2.7183; gamma=0.1333; k = [1,9,23,7,23,9,20,29,63,102,73,59,27,130,75,185,70,92,326]; Rt=0:0.01:10; P = zero...

16 days ago | 1

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Newton's method iterations
I suggest you plot a graph of your function, then you can see where good initial estimates would be. For example f = @(x) 2*ex...

17 days ago | 0

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the variable appears to change size every loop iteration
Answered here: https://uk.mathworks.com/matlabcentral/answers/1464024-the-variable-appears-to-change-size-every-loop-iteration?s...

18 days ago | 1

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Dealing with NaN Values
Try find(isnan(data))

18 days ago | 0

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Writing the dirac function as a function handle
Try dirac_i = @(x) x==i; % This assumes i has been fixed before the function is defined

18 days ago | 0

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Answered
How to plot 2 graphs with input as a range and join them together?
Like this p0=0; p1=6; p2=1; p3=3; p4=3; t=[0:0.01:1]; x1 = (1/6)*[((((-t).^3)+(3*(t.^2))-(3*t)+1)*p0)+(((3*(t.^3))-(6*(t....

18 days ago | 0

Answered
the variable appears to change size every loop iteration
You don't need the loop: If = [0 0.5 1.0 1.5 2.0 2.5]; Ea = [0 75 150 205 242 270]; Ra = 0.14; RI = 2; la = 100; Ifield = ...

18 days ago | 1

Answered
Unable to find solution to matrix using Gauss Seidal code. How should I proceed to get the solution?
You are dividing by A(i,i) some of which are zero. These will introduce NaNs.

19 days ago | 0

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Solving Eqn with Varying Variable (Ms)
Like this: a1a4 = 1./[1, 2, 4, 10]; n = 10000; p4p1 = 1:n; M = zeros(numel(a1a4),n); for j = 1:numel(a1a4) m = 1.01; ...

21 days ago | 1

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Answered
To solve two 2nd order coupled differential equation using ODE45?
Replace each 2nd order ODE by two 1st order ODEs. e.g. set V1 = X1', V2 = X2', then V1' = (50*sin(f(t) - V1)*V2')/sin(f(t)), V...

22 days ago | 0

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Answered
Using Ode45 to solve dynamics problem (ISA model)
Like this z0 = 39045; %const.h0; v0 = 0; %const.v0; t0 = 0; tf = 800; N = 60000; tspan = linspace(t0, tf, N); X ...

22 days ago | 0

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Answered
Curve fitting a power law function
Like this? h0=0.654; %[m] This seems to be unused h_t=[0.654;0.628;0.604;0.582;0.56;0.54;0.52;0.501;0.482;0.465;0.447;0.43;0.4...

24 days ago | 0

Answered
Finding approximate real solution to a equation
You don't need syms here. Try the roots function. help roots

26 days ago | 0

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Answered
Two Step Adam Bashford Method
As follows f=@(t,y) 3*t+y/t; alpha=5; a=1; b=2; n=3; [t, w, h] = abs2(f, a, b, alpha, n); plot(t,w,'-o'),grid xlabel('t'...

27 days ago | 0

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Answered
How to add iterations in Newton Raphson code of Kepler Equation
Like this M = 0.908; e = 0.725; tol = 10^-6; [E, its] = Kepler(M,e,tol); disp(['E = ' num2str(E) ' after ' num2str(its), ...

27 days ago | 0

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Answered
Let x=[2 4 6 8 10] and y=[1 3 5 7 9]. Compute for the vector z whose elements are equal to z= (xy+ y/x)/[(x+y)]^((y-x)) + 10^(x⁄y)
You need z = (((x.*y)+(y./x))./((x+y).^(y-x)))+10.^(x./y) % another dot here ^

27 days ago | 0

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Answered
how to find the root of function?
Like this? n_h0 = 0.1; %initial guess n_h = fzero(@n_h_fun, n_h0); disp(n_h) function a=n_h_fun(n_h) alpha=0.74; ...

28 days ago | 1

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Answered
Newton's method for 2 dimension vectors
LIke this? % Functions f = @(XY) [XY(1).^3 - 3*XY(1).*XY(2).^2 - 1; 3*XY(1).^2.*XY(2) - XY(2).^3]; J = @(XY) [...

29 days ago | 0

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How to plot a (which is changing from 0-1 in 0.01 increments) vs x(2) (using a for loop and fsolve to find the solution of a nonlinear equation containing x(s) sol based on a
Your first equation is a simple quadratic in x(1); your second is a quadratic in x(2) that depends on x(1), so, assuming you are...

1 month ago | 0

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