Alan Stevens
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Contribute at least one answer each month for 12 consecutive months
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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; ...
1 day ago | 1
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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...
2 days ago | 0
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 ...
2 days ago | 0
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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...
4 days ago | 0
Finding approximate real solution to a equation
You don't need syms here. Try the roots function. help roots
6 days ago | 0
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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'...
7 days ago | 0
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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), ...
7 days ago | 0
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 ^
7 days ago | 0
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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; ...
8 days ago | 1
| accepted
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) [...
9 days ago | 0
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...
12 days ago | 0
to plot alpha(a) vs diameter(D) in the given problem. where A = l*sin(b), B = l*cos(b), C = ( h + 0.5*D )*sin (b) − 0.5*D*tan(b) and E = ( h + 0.5*D)*cos(b) − 0.5*D.
Try replacing D within the j-loop by D(j). Also add something like alpha(j) = a after the end of the i-loop (but inside the j-l...
13 days ago | 0
Solving factorial equation with integer variables: Empty sym 0-by-1
Set x-2 = 659 and y-x = 679 for one solution, and x-2 = 679 and y-x = 659 for another.
14 days ago | 0
Unable to plot exponential graphs properly
One possibility t = linspace(-10,10,400); y1 = exp(t); y2 = exp(-t); y3 = exp(2*t); plot(t,y1,t,y2,t,y3) legend('y1','y2...
16 days ago | 0
Not enough input arguments.
Like this?: global PT S DELH Q CPA CPB CPC CPD NA NC NB ND NE NT PT = 1.5; % PT is total pressure in atmospheres S = 0.05; %...
16 days ago | 1
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speed up integrating the same function over many overlapping intervals?
How about using cumtrapz to do the cumulative integral from 0 to max(X) just once, then select the sections specified by X(i).
18 days ago | 0
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Solving single variable equation where other variables depends on that single variable
Try using fzero. For example: f = @(x) x.^2 +1./x; % arbitrary function: replace with your own y = @(x) f(x); z = @(x)...
18 days ago | 0
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last value of array
Do you mean something like this %plot n vs x n vs y for n=1:10 [t,r]=ode45(@fn,[0 14],[0.01+n 0.01 ]); xlast(n) = r(end,1);...
28 days ago | 0
How to keep both readability and calculation speed when using anonymous functions?
How about something like hexp = @(x,y) exp(1i*(x+y)); x = ..; % set to whatever is required y = sqrt(x.^2 + A^2); h1 = h...
1 month ago | 0
Non-linear system of inequalities
First plot some lines that bound the inequalities % G>21 % 15<=S<=18 % 61<=2S+G<=63 % 30<=atan(S/G)<=45 -> sqrt(3)/3 <= S/...
1 month ago | 1
How to request a specific user input?
You don't need "input" twice: prompt = 'Please enter 1 for EXP1 and 2 for EXP2:'; % ask EXP = input(prompt); if ...
1 month ago | 0
Same time steps for ODE function and OutputFcn
You could simply calculate k = x.^2 + y.^2; immediately after [x,y] = ode45(@myode,tspan,1,options); However, have you real...
1 month ago | 0
Please how do I show multiple custom equations fittings for a data set on the same Graph/Figure?
Use the "hold on" command after the first plot. help hold
1 month ago | 0
Error in multipying a 3 by 3 matrix with a 3 by 1
Check that the number of columns in the first matrix matches the number of rows in the second matrix. Ri has 3 columns, C has 3...
2 months ago | 0
Any mathematical mistake in my script ?
Easier to check like this b=1; t=1; br=1; Pr=1; d = @(n) (2*n + 1)*pi; c = @(n) d(n).^2; k1 = @(n) ( 1 - exp( -c(n)*t/(4...
2 months ago | 0
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How to solve a 2nd-order ODE system with space-dependent variable with ODE45?
More like this perhaps dY = [0, 0.0026, 0.0082, 0.0138, 0.0194, 0.0250, 0.0306, 0.0362, 0.0418, 0.0475, 0.0532, 0.0589, 0.0647,...
2 months ago | 1
| accepted
Trapezoidal integration for pressure
Do you mean something like this? x = [0.025 0.0233 0.0243 0.02477 0.0254]; z = [0.3658 0.3722 0.3991 0.433 0.477]; P = [24...
2 months ago | 0
How to solve this 4th order linear ODE with ode45?
You need to define tspan x_1_0 = [2; 1/2; 0; 0]; tspan = [0 10]; %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% [t_1,x_1] = ode45(@f, tsp...
2 months ago | 0
Theta phi positive and negative conventions and conversions
Try mod(theta,180) and mod(phi,360)
2 months ago | 0
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I'm trying to solve Bernoulli equation in differential form.
If p is constant then dp/dx = 0, hence du/dx = 0, which means u is constant. If you meant the pressure gradient is constant the...
2 months ago | 0
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