Thread Subject: function in m file

I need help to run this code in a M file, Is there any body who has an idea why this code is not runing
 %
% Main program for the numerical integration of
% the PDE modeling heat conduction in a solid slab.
%
 
global n length;
%
% set the initial conditions
%
n = 51; % Number of grid points (including boundaries)
length = 1; % Length of the slab
dx =length/(n-1);
%
% Initial conditions definition
%
for i = 1:n,
x (i) = (i-1)*dx;
tic (i) = 100*sin(pi*x(i)/length);
end
 tspan = linspace(0,1);
%
% Integration of the discretized PDE system

%
[time,temp] = ode15s('fcn',tspan,tic);
[lastp,nn] = size(time);
plot(temp(1,1:n)),hold,xlabel('x'),ylabel('T')
for i = 2:lastp,
plot(temp(i,1:n))
end
 
function fx = fcn (time,t)
global n length
%
% left boundary condition
%
t (1) = 0;
%
% right boundary condition
%
t (n) = 0;
%
% first-order derivative tx
%
tx = dss002 (0,length,n,t);
%
% second order derivative txx
%
txx = dss002 (0,length,n,tx);
%
% return the discretized value of the second order derivative
%
fx = txx';
end
function ux = dss002 (xl,xu,n;u)
%
% Function dss002 computes the first derivative, "ux", of a
% variable "u" over the spatial domain xl .le. x .le. xu from
% the classical three point, second order finite difference approximations.
%
% Inputs:
% -------
% xl = lower boundary value of x
% xu = upper boundary value of x
% n = number of grid points in the x domain
% including the boundary points
% u = one dimensional array containing the value of u at
% the n grid points for which the derivative is to be computed
%
% Outputs:
% -------
% ux = one dimensional array containing the numerical values of
% the derivatives of u at the n grid points
%
% Matlab version written by: Antonio Flores T./ April 2002
%
%
% Spatial increment
%
dx = (xu-xl)/(n-1);
r2fdx = 1/(2*dx);
nm1 = n-1;
%
% Equation (12)
%
ux (1) = r2fdx*(-3*u(1)+4*u(2)-u(3));
%
% Equation (9)
%
for i = 2:nm1,
ux (i) = r2fdx*(-u(i-1)+u(i+1));
end
%
% Equation (13)
%
ux (n) = r2fdx*(u(n-2)-4*u(n-1)+3*u(n));
%-- End of the dss002.m file --
end

Dear ee!

> I need help to run this code in a M file, Is there any body who has an idea why this code is not runing
> %
> % Main program for the numerical integration of
> % the PDE modeling heat conduction in a solid slab.
> % ...

Please tell us what "code is not running" means. Describe the output and the expectations, the exact error message (if one appears) and the corresponding line.

Kind regards, Jan

 Thank you very much,
this is the error msg "??? Error: File: mat.m Line: 32 Column: 1
Function definitions are not permitted at the prompt or in scripts."

with this code i would like to discretize a pde using the method of lines

The outpout should be the plot of my new set of equation

Dear ee!

> this is the error msg "??? Error: File: mat.m Line: 32 Column: 1
> Function definitions are not permitted at the prompt or in scripts."

You cannot define a function inside a script.
So at first read the documentation about functions and scripts.
Then I'd recomment to create functions also, because this reduces conflicts in the main workspace - but this may be a question of taste.

Kind regards, Jan

"ee " <sarkinkarfi@hotmail.com> wrote in message
news:heimbv$52t$1@fred.mathworks.com...
> Thank you very much,
> this is the error msg "??? Error: File: mat.m Line: 32 Column: 1
> Function definitions are not permitted at the prompt or in scripts."

Your M-file is a script file, not a function file.

http://www.mathworks.com/access/helpdesk/help/techdoc/matlab_prog/f7-38085.html

As the error states, you cannot define a function inside of a script M-file
(or at the MATLAB prompt.)

Either convert your script file into a function file or move the functions
in the script file into their own function M-files and just call them from
in the script.

--
Steve Lord
slord@mathworks.com
comp.soft-sys.matlab (CSSM) FAQ: http://matlabwiki.mathworks.com/MATLAB_FAQ