Re: What's the correct order of things in a file? (beginner's question)

[Robert A. Macy]

Here is a sample function program called
 ppm.m

It shows decent practice for "help" section and error
checking inputs that go into the function.

WATCH OUT FOR WORD WRAPPING ! ! !
=-=-=-=-=-=start of file=-=-=-=-=
function [output,outputrms]=ppm(input,start,stop);
%       PPM  returns the parts per million error from the mean of
the matrix 
%       use form [output, outputrms]=ppm(input,[start, stop]);
%       where input is a matrix
%       returns the ppm variation and a vector showing rms of
that variation
%       optional start and stop reference where the average is
taken
%               default is 1 and rowsinput, or end

if (nargin==0)
  help ppm;
  return;
endif

if (nargin>3)
  error("only one, or three, arguments \n");
  return;
endif

if (nargin==2)
  error("if define start, must define stop \n");
  return;
endif

[rowsinput,columnsinput]=size(input);
if (rowsinput==1)
  error("input must have at least two rows \n");
  return;
endif

if (nargin==1)
  start=1;stop=rowsinput;
endif

if ( (isscalar(start) !=1) + (isscalar(stop) != 1) )
  error("start and stop must be single real integer values
/n");
  return;
endif

if ( (abs(mod(start,1)) != 0) + (abs(mod(stop,1)) != 0) )
  warningmsg="start and stop should be integers, rounding
off... "
  start=round(start);stop=round(stop);
endif

if (start >= stop)
  error("start cannot be equal to, or larger than, stop
\n")'
  return;
endif

if (stop > rowsinput)
  error("stop is outside range of input \n")'
  return;
endif

inputave=ones(rowsinput,1)*mean(input(start:stop,:));
output=2000000*(input-inputave)./(abs(input)+abs(inputave)+eps/1e12);

test=abs(output)-ones(rowsinput,1)*mean(abs(output));
outputrms=sqrt(mean(test.*test));

=-=-=-=-=-=end of file=-=-=-=-=-=



On Mon, 13 Jun 2005 18:48:13 -0700
 David Collett <address@hidden> wrote:
> Hi, Robert.
> 
> Thanks for helping me.
> 
> This makes a lot more sense now. I can see the advantages
> of saving a  function as a separate file to reuse with
> other scripts.
> 
> I'll try it the way you suggest tonight.
> 
> Thanks again.
> 
> David
> 



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