# Alan Stevens

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**Content Feed**

How to solve two coupled differential equations using ode45.

"Why is my previous code is not working properly by treating the problem to be a DAE." I don't know! "Also I noticed you wrote...

5 giorni ago | 1

Multiple Anonym Function return wrong values

Here's one solution: C = [4622 5480 18923]*1e-12; U = [454e3 454e3-20e3 20e3].*sqrt(2); W = Energy(C,U); disp(W) function W...

5 giorni ago | 0

| accepted

Hi, is it possible to have variables in an ode45 that varies according to another function?

Put something like [T, p, rho, speedsound] = atmos(height); immediately after height = x(1); in function dynameqn. Not sur...

13 giorni ago | 0

root finding and plot of graph

Are you looking for something like this? hi = 1e-6; lo = 1e-9; n = 500; dt = (hi-lo)/n; t3 = lo:dt:hi; y = f(t3); subplo...

13 giorni ago | 0

Calculator result and MATLAB result are different

Have you checked that both are using degrees, or both radians? The Matlab as you've written it is using radians (use sind(24) a...

16 giorni ago | 1

How can I rotate a set of points by an angle around its origin?

Do you mean like this? ITM = [461400.0758 617474.3059 461400.8069 617475.4609 461400.8069 617475.4609 461402.3069 617477.633...

18 giorni ago | 1

| accepted

Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.

Try replacing x(4) = Velocities(3608.9,5249.3); by x(4,:) = Velocities(3608.9,5249.3); Same for x(5).

21 giorni ago | 0

Removing zeros from matrix

Like this? A = [1 2 3 4 5 6; 1 2 3 4 5 6; 1 2 3 4 5 0; 1 2 3 4 0 0; 1 2 3 0 0 0]; B = A'; B=B(:); B(B==0)=[]

circa 2 mesi ago | 0

Error in ODE arguments

I suspect you mean like this (notice the way M divides, using the back-slash): % Numerical solution of IVP % M*xddot + C*x...

circa 2 mesi ago | 2

| accepted

How to Approximate The Solution for an Initial Value Problem?

Try f = @(t,x) [x(2); sin(1.9*t)-4*x(1)]; [t,x] = ode45(f,[0,150],[1,0]); plot(t,x)

circa 2 mesi ago | 1

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Creating a set range for a function

(x < 3) && (x > 25) An individual element of x can't be both less than 3 and greater than 25 at the same time. If here are ma...

circa 2 mesi ago | 0

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Plotting the tangent line for newton raphson method

Like this? fx = @(x) x.^2 -2; dfdx = @(x) 2*x; n_step = 7 ; % Anzahl der durchzuführenden Schritte für Newtonverfahren...

circa 2 mesi ago | 0

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Fit scatter plot with a curve

More like ths? x = [0.2337;0.296;0.3071;0.4208;0.2055;0.9597;0.8683;0.243;0.3363;0.2793;0.5292;0.2471;0.2282;0.4774;1.0392;0.43...

circa 2 mesi ago | 1

| accepted

Generating random numbers with a different probabilities

Assuming there are just two levels of probability, and that the numbers are real, not just integers, you could try: p50 = 0.75;...

circa 2 mesi ago | 1

Hi, what does ; exactly mean?

It means start a new row, e.g. x = [1 2; 3 4]; disp(x)

circa 2 mesi ago | 0

Solve the IVP y′′′=sin(y2)+y′+cos(t), provided with an appropriate set of initial conditions of your choice, and using Matlab's ODE45 function.

Like this? (Note the IC for d^2y/dt^2 must be consistent with the values chosen for y(0) and dy(0)/dt). Change the IC's and tim...

2 mesi ago | 0

Need Help Solving System of ODEs

You haven't included the first term on the right-hand side of your equation for dV/dt, nor for dgamma/dt.

2 mesi ago | 1

spring mass using ode45

Like this x0 = [0; 0]; tspan = [0, 10]; [t, x] = ode45(@func, tspan, x0); subplot(2,1,1) plot(t, x(:, 1)); grid('on...

2 mesi ago | 0

I am getting error in this program. Please suggest the corrections.

Change c = [1 2 2 3 4 5 6 7]; to c = [1 2 3 4 5 6 7];

2 mesi ago | 1

Hello, I'm trying to plot one non-piecewise function and two piecewise functions in one graph but I keep getting an error. I don't understand the two error messages below.

You need to put the non-local functions at the end, as in the following. There were several other errors. I don't know if my co...

2 mesi ago | 0

How to Solve equation using Eulers method in Matlab?

Here's part (a) for you - definitely not a straight line!

2 mesi ago | 0

| accepted

I need to set up a Runge Kutta solver for water leaving a bucket through a certain diameter nozzle as function of time, it says array indices must be positive integers/log val

Indices in Matlab start at 1, not 0, so you need for i=1:60:200 not for i=0:60:200

2 mesi ago | 0

How to get one output for each input into an equation in MATLAB?

mu = mu_max * (x./(x+Ks)); % Notice it is ./ not just /

3 mesi ago | 0

How to solve 'Index number exceeds number of array elements(1)'

You don't update XSOL, so when ct is 2, XSOL(ct) doesn't exist.

3 mesi ago | 0

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A question about FitzHugh-Nagumo model

Like this? tspan = [0 100]; v0 = 0; w0 = 0; IC = [v0 w0]; A=0.5; B=0.05; Epsilon=0.005; I=@(t)sin(t); %%%%%%%%%%%%%%...

3 mesi ago | 0

| accepted

How to find parameters that minimize a difference

Use fminsearch and use the norm of the differences. help fminsearch

3 mesi ago | 2

I want to combine 2 variables in matlab into one variable

If they are imported as, say, c1 and c2, then you can simply write c = [c1; c2]; then delete the c1 and c2 if you don't need t...

3 mesi ago | 0

| accepted

How can i call an equation and it's derivative inside a matlab function?

Like this, perhaps: % TC is given in terms of percentage! x0=0; TC=10^-4; error=TC+1; i=0; x(1)=x0; while(error>TC) [f...

3 mesi ago | 0

simple Fixed Point Iteration

Probably more like this (though you don't seem to have used function f anywhere): n = 11; x = zeros(1,numel(n)); ea = zeros(1...

3 mesi ago | 0

| accepted

I want Estimate log to the base 10 value using 'x' number such that 10^estimated value is equal to or just exceeding x.

< not <= a = log10_bywhile( 50, 0.1 ) b = log10_bywhile( 100, 1 ) function [out] = log10_bywhile(x, inc) esmt = 0; % if...

3 mesi ago | 0

| accepted