Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!dsi!dave
From: dave@dsi.COM (Dave Rifkind)
Newsgroups: comp.lang.c
Subject: Re: Style for handling matrices in C
Message-ID: <278@dsi.COM>
Date: 16 Oct 89 07:30:01 GMT
References: <7229@cognos.UUCP>
Reply-To: dave@dsi.UUCP (Dave Rifkind)
Organization: KFW Corporation, Newbury Park, CA
Lines: 24

In article <7229@cognos.UUCP> alanm@cognos.UUCP (Alan Myrvold) writes:
>So my question is, what C style SHOULD become commonplace for
>allocating matrices....

Here's one that doesn't require any special action to free up the
matrix:

     double **mat_alloc(row, col)
     {
	  int i;
	  double *dp, **dpp;

	  dpp = malloc(row * sizeof(double *) + row * col * sizeof(double));
	  if (dpp != NULL) {
	       dp = dpp + row;
	       for (i = 0; i < row; i++)
		    dpp[i] = dp + i * col;
	  }
	  return dpp;
     }

This is off the top of my head and may not make sense.  The idea is to
put the pointer array and all of the row arrays in a single allocated
block.  To get rid of it, you just free it.