What's wrong with this dynamic matrix allocation

[Paul E. Johnson]

Every now and then I try to extend my horizons.  

All it gets me is aggravation.  I found the C-FAQ for the usenet group
on C and some examples of how to allocate a dynamic matrix in which the
rows are of variable length. 

In my example, there are NOFSPACES rows and the number of columns of
each is given by Dimensionality[s].  Whenever I try to write on one of
the elements in my matrix, such as minValue[0][0], I get a seg fault and
the bt points at the command that accesses it.  HEre's my example

----------------interface ------------------------
@interface MultiDimSpace: SwarmObject {
        float ** minValue;
        float ** maxValue;
  }

----------implementation-----------------------------

#import "MultiDimSpace.h"
#import "Point.h"
#import <misc.h>

@implementation MultiDimSpace
-createEnd
{
  int s;
 
  [super createEnd];
  minValue = xmalloc(NOFSPACES * sizeof (float * ));
  for(s = 0; s < NOFSPACES; s ++)
    {
    minValue[s] = xmalloc(Dimensionality[s] * sizeof(float));
    }

  maxValue = malloc(NOFSPACES * sizeof(float *));
    for(s = 0; s < NOFSPACES; s ++)
    maxValue[s] = xmalloc(Dimensionality[s] * sizeof(float));

}
-setMinSpace: (int) space Dim: (int) dim To: (float) value
{
minValue[space][dim]=value;
return self;
}

int NOFSPACES 
and 
int Dimensionality[NOFSPACES]
are Global variables defined elsewhere. I've put in "printf" statements
to make sure that the  values of NOFSPACES and Dimensionality[s] do
exist when that createEnd method is run.

Here is an example of commands from ModelSwarm that crash and the bt
points at the setMinSpace message sent to world.
 
   world = [MultiDimSpace createBegin: [self getZone]];
   world = [world createEnd];
   for(s=0;s<NOFSPACES;s++)
   for(i=0; i < Dimensionality[s] ; i++)
   {
        [world setMinSpace: s Dim: i To: 0];
   }
-- 
Paul E. Johnson                       email: address@hidden
Dept. of Political Science            http://lark.cc.ukans.edu/~pauljohn
University of Kansas                  Office: (785) 864-9086
Lawrence, Kansas 66045                FAX: (785) 864-5700

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