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Alan Stevens


Last seen: Today Active since 2020

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Answered
Optimizing code for HAC Weight matrix generation - How to be faster?
Try replacing the loops with something like this: i = (1:size(Weight_correlation,1))'; j = 1:size(Weight_correlation,2); c = ...

5 hours ago | 0

Answered
How to a create a label at the bottom of a vertical line?
Like this? x = linspace(0,6,100); y = exp(x); plot(x,y) xline(4.5,'-',{'Acceptable','Limit'}, 'LabelVerticalAlignment', 'bot...

3 days ago | 0

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Answered
Secant method Nan Error
You haven't updated error in your while loop. Try including something like error = abs(X0-X1);

4 days ago | 0

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Answered
Function error in ODEs RK4 method, solving 6 unknowns
It works for me (I've commented out the fprint statements in the code below - but it works with them in!): global CDin psi thet...

11 days ago | 0

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Answered
I keep getting the error using '/'.
Try mu_ratio=(1-(vol_frac(c,1)/0.605).*((particle_ratio(c,1)).^1.2)).^(-1.5125); Notice the dots! .* .^ Difficult to be...

11 days ago | 0

Answered
Plateau followed by one phase decay
Like this? x = 0:0.5:20; % time in seconds Y0 = -0.6; % signal baseline value Plateau = -1; % singnal plateu after trigger/st...

22 days ago | 1

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Answered
Radiation view factor using Monte Carlo
I think you probably need cos(theta), rather than theta, to be linearly spaced.

1 month ago | 0

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How to fix a syntax in the oscillator's plot code?
Like this (both x_1 and x_2 are contained in y) T0 = 10; omega0 = 1; M = 1; F = 1; x_1 = 0; x_2 = 0; x_0 = [x_1 x_2]; ts...

1 month ago | 0

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Answered
ODE45has long runtime and graph will not plot
Here's my attempt to make sense of your equations tauspan = 0:100:10000; % p0 = [0.5 0.5 0 0]; % dp1dt = -rf + rr % dp2...

2 months ago | 0

Answered
Two graphs in the same plot, why?
Something like this data = xlsread('sunHoursInTrollhattan.xlsx'); mins = data(:,1)*60 + data(:,2); plot(1:12, mins,'o'),grid ...

2 months ago | 0

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Answered
Two graphs in the same plot, why?
You have the hours as one plot and the minutes as the other! Turn the data into all minutes, or all hours first.

2 months ago | 0

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Could anyone help me in fixing the problem in my code for solving the initial value problem numerically: y'=y^2, y(0)=1?
Here's an attempt using fminsearch. I don't know anything about the Obreschkoff method, so couldn't say if your equations are...

2 months ago | 0

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Answered
I get this message(Attempted to access F(5); index out of bounds because numel(F)=4.) when I run the code below..
In fsode you try to use F(7) when calculating F(5), before you have calculated F(7)!

2 months ago | 1

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Answered
Laser Rate Equation Modelling
Like this? (Look at lines 27, 28 and 38) %Script % Define model parameters temperature = 25; wavelength = 1.312e...

2 months ago | 0

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Determine the coordinates of the nodes forming the outermost circle
Here's an alternative way: nodes = importdata("nodes.mat"); figure plot3(nodes(:,1),nodes(:,2),nodes(:,3),'b.','Markersize',1...

2 months ago | 0

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Problem with fitting a loglog plot
polyfit doesn't like the log of zero. One option is to remove the first row of the data: data_exp_high = load("data_Q_1e-8.txt...

2 months ago | 0

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Index in position 2 exceeds array bounds (Index must not exceed 1) errors?
N0 is a 4x1 vector, but you call it with two indices in the for loop! Turn N(1,j) into N(1) and similarly for the other calls t...

2 months ago | 0

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Answered
How do I solve this ODE system where there exists derivatives in both sides?
You can separate the terms as follows:

2 months ago | 0

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why am i getting grey figure box can someone fix please
Making some assumptions about your function pendulumODE, I think the following is more like what you expect to see: % Constants...

2 months ago | 0

Answered
Algae growing, concentration curve problem
Increase nt to 10000 and it works just fine for T = 20000.

2 months ago | 0

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Error ''Array indices must be positive integers or logical values.'' when putting interval of 0.01 in a for loop
More like this: k = 0:0.1:2; n = numel(k); for i = 1:n x(i) = k(i); y(i) = k(i)*k(i) + 3*k(i) - 4; end plot(x,y...

3 months ago | 0

Answered
Trying to code from Polymath
Like this for example (I'll leave you to extract the numerical values): Wspan = [0 2]; % Integration range % Initial valu...

3 months ago | 0

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Unable to solve differential equation with finite difference method
Should be more like this I think: b = 0.02; m = 80; L = 0.7; g = 9.81; J = m * L^2/3; a = 0; bet = 2; alpha = 0; beta = 3...

3 months ago | 0

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FDM using succsesive overrelaxation method,
For w1 and T1 you have w1(:,Nx1+1) = (((la*B1*dx1)/(dx2*A1))*(w2(:,2)-w2(:,1)))+w1(:,Nx1); %Continuity of shear stress ...

3 months ago | 0

Answered
Solving first order ODE with initial conditions and symbolic function
You can do it numerically as follows: % input parameters Tinf=70+273.15; Ti=20+273.15; d=15e-2; r=d/2; cdepth=10/1100; Tf...

4 months ago | 0

Answered
can someone help me to analyze this program? How does the flowchart look like?
Perhaps this will help: %radiasi benda hitam % constants h=6.626e-34; c=3e8; k=1.38066e-23; % range of values lambda ...

4 months ago | 0

Answered
Error using surf (line 71) Data dimensions must agree
More like this? for it=1:2 for jt=1:3 zt(it,jt)=it+(jt-1); end end [x,y] = meshgrid(1:3,1:2); figure; surf(x...

4 months ago | 1

Answered
How to find Basins of attraction for the Halley method?
Don'tforget the dot multiply: f = @(z) z.^3 +1; df = @(z) 3*z.^2; ddf=@(z) 6*z; % its roots r1 = -1; r2 = 1/2 + 1i*...

5 months ago | 0

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Answered
"Invalid use of operator." doesn't go even after trying various solutions :(
Why nor just use Matlab's inbuilt cart2pol function?

5 months ago | 0

Answered
Heat equation using Boundary condition
function statements of this form (i.e. functions eq1, initial and ba) need to go at the end of the script, not the start.

5 months ago | 0

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