Question

Converting anonymous function to a matrix
I have a function of the form: , which I want to evaluate. I could do this old school with a double loop but that would take t...

3 hours ago | 1 answer | 0

Question

Diagonal matrices with spdiags
I'm working on a numerical solution to an equation and as part of this I have to solve a matrix solution. The system of equation...

2 months ago | 1 answer | 0

Question

Is there a way of removing these for loops to speed up my code?
I have the analytical solution to the following PDE: with boundary condition and and initial condition in the form of a Gr...

2 months ago | 1 answer | 0

Question

I have: Error using bsxfun Non-singleton dimensions of the two input arrays must match each other.
So I have some code which I want to get working and I don't understand the error which is being given to me which is: Error usin...

2 months ago | 2 answers | 0

Question

Interp1 returns NaN for a value
I have some data (x,f(x)) where 0<=x<=1 and I have N points. I wish to obtain f for an inteverval [a,b] which is well within the...

2 months ago | 1 answer | 0

Question

Tracking the size of a variable
Hi, I have a vector of length 200. When I run my program it somehow halfs in length, and I have no idea why. Is there a way of ...

9 months ago | 1 answer | 0

Answered
Not enough input arguments when doing global optinisation
I've seen what I need to do. The set up of the function is different to lsqcurvefit: I had to define the function as: fun = ...

10 months ago | 0

Question

Not enough input arguments when doing global optinisation
I am trying to use the global optimisation toolbox to find some parameters which will make a computed curve overlay some experim...

10 months ago | 1 answer | 0

Question

lsqcurvefit doesn't curve fit
I have a model which I want to paramtrise using lsqcurvefit. I have 10 parameters that I must find and I have 10 pieces of data ...

10 months ago | 2 answers | 0

Question

Error using lsqcurvefit (line 262) Function value and YDATA sizes are not equal.
I am using the following code: %Import data as time and voltage: load VoltageData.mat; load('OCP_Cathode.mat'); %Load the O...

10 months ago | 1 answer | 0

Question

Finding the multiple zeros within a prescribed interval
I wish to solve the nonlinar function: =0 within a prescribed interval, say (0,100] say, I'm aware of usi...

1 year ago | 1 answer | 0

Question

Optimisation of parameters in a PDE
Hi, Suppose I am dealing with the heat equation: ∂T/∂t=α∂^2T/∂x^2 and I have some data which I want to fit it to and determ...

1 year ago | 1 answer | 0

Question

Solution diverges for 1D heat equation using Crank-Nicholson
I am trying to solve the 1D heat equation using the Crank-Nicholson method. I have managed to code up the method but my solution...

1 year ago | 1 answer | 0

Answered
System of PDEs which is tricky for PDEPE
I have some values which allow the code to run BUT I have oscillations in the diffusion which I should not get. I am assuming th...

1 year ago | 0

Answered
Variable density in heat diffusion equation
So I used the following code: function [CC, FF, SS]=battery_GE(x,t,u,DuDx) global rho; global c_th; global a_1;globa...

1 year ago | 0

Answered
Variable density in heat diffusion equation
So I do the interp1 trick you demonstrated before?

1 year ago | 0

Question

Variable density in heat diffusion equation
Suppose I have a heat diffusion equation: rho(x)*c(x)*dT/dt=d/dx(k(x)*dT/dx) Where rho(x) is the density, c(x) is the heat...

1 year ago | 2 answers | 0

Question

Problems with pdepe and input variables
I have played around with my code and have the following code for pdepe which looks as if it should work: function battery_...

1 year ago | 0 answers | 0

Answered
System of PDEs which is tricky for PDEPE
So I managed a work around to get pdepe to work with my system and the code I'm using is: %This is the simplistic model of ...

1 year ago | 0

Question

System of PDEs which is tricky for PDEPE
I have a system of PDEs, mainly diffusion equations of the form: T_t-(k(x)(T_x)_x=a*E^2 c_t-(D(x)*c_x)_x=d*(E_x+c_x-T_x) ...

1 year ago | 5 answers | 0