creating a plot of a self-defined function

[Erik Leunissen]

Hi all,

As a newcomer to octave, I've been experimenting with functions and 
plots, but I fail to create a plot of a self-defined function. Here is 
what I do:

In a function file myfunc.m I've got:

function C = myfunc (x,t)
        global M A v Dx k;
        C=M/A*exp(-(x-v*t)^2/(4*Dx*t)-k*t)/(2*sqrt(pi*Dx*t));
endfunction

In another file "parameters.m", I've got default values for the 
variables M, A, v Dx and k.

In octave at the command line, I first check whether the function myfunc 
works:

octave:1> source parameters.m
octave:2> myfunc(2,3)
ans =  5.2180

OK. Next creating the plot, analoguous to section 15.2.2.2 of the manual:

octave:3> C = @(x,t) myfunc (x,t);
octave:4> ezmesh (C, [-5, 10, 0, 10]);
warning: matrix singular to machine precision, rcond = 0
warning: matrix singular to machine precision, rcond = 0
octave:5>

This results in a separate window with a 3D grid popping up, but it 
contains no plot.

I'm familiar with each of the words in the warning message (except for 
the phrase "rcond = 0"). But the sentence as a whole doesn't mean 
anything to me yet.

Could somebody please provide me with some directions to help me make 
progress with this 3D plot?


Thanks in advance,

Erik Leunissen.