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Alan Stevens


Last seen: 1 day ago Active since 2020

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Answered
How to define and plot a function with input range?
Like so: pt = @(t) (1 ./ (1 + t .^ 2)).*(t>=-0.5).*(t<=0.5); x = 0:0.01:10; y = 2*pt(x-1) + 4*pt(x-2) + 3*pt(x-3) + pt(x-4); ...

1 day ago | 0

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Answered
Plot the slope of a parabola with only the data points being known
Like this? x = linspace(-0.5,0.5,25); %length in (meters) def_3mm_no_grav = -[0.00 5.82e-1 1.08 1.53 1.94 2.30 2.62 2.89 3.12 ...

1 day ago | 1

Answered
SIRE with vaccine model
Like this tspan = [0 1.5]; options = odeset('Refine', 10, 'RelTol', 1e-4); y0 = [5185000*0.3 5185000*0.7 1 1 0 0 0 0]; [t,...

1 day ago | 1

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Answered
Problem with fplot function - displays grey zone instead of functions
Change all the ^ to .^ (i.e. dot^)and the * to .*

2 days ago | 0

Answered
I would like to create a handle function by for loop in matlab, but it does not work. I will be thankful if some body help me.
More like this? sfn = @(x,a,b) (a - b)*x; a=[1 2 3]; b=[4 5 6]; n=length(a); x = 1; % specify whatever x value you want f...

2 days ago | 0

Answered
How to solve this implicit equation in matlab?
Good idea to plot a graph first, to see roughly where the root lies. Then use fzero. For example:: fn = @(x)log((0.77*x-0.77)...

3 days ago | 0

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Problem with solving discrete element method using leap frog method
The following gets the code working, but I've no idea if the results are meaningful!! n_part=4; kn=5; kt=2/7*kn; m=0.3; g=9...

4 days ago | 0

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Answered
Write a loop to plot a model graph
A little more like this. You need a smaller value of dv and a while loop. The fit isn't very good! %% Observed Wave dispersi...

4 days ago | 0

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Answered
Making a line thought points plotted from for loop in MATLAB
Like this? R1= 1399.580e+6; C1= 374.868e-6; R2= 1497.005e+6; C2= 350.472e-6; R3= 19573.407e+6; C3= 2429.373e-12;...

5 days ago | 0

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Answered
How do I plot and return the values of multiple intersections between a function and zero?
Here's one possibility (though you get repeated results for the roots!): det_a = @(x) sin(x).*cosh(x) - cos(x).*sinh(x); x=0:1...

6 days ago | 0

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Answered
Simplify Matrix decimal to integers
One way is M = [881/2158 985/1393 780/1351 881/2158 -985/1393 780/1351 -881/1079 ...

6 days ago | 0

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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...

9 days 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 ...

11 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...

11 days ago | 0

Answered
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...

18 days ago | 0

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

18 days ago | 0

Answered
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 ]; ...

19 days ago | 0

Answered
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) ...

19 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) ...

20 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...

20 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...

23 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...

23 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...

23 days ago | 1

Answered
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...

24 days ago | 0

Answered
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...

25 days ago | 1

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

25 days ago | 0

Answered
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

25 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....

25 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 = ...

25 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.

26 days ago | 0

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