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[Frama-c-discuss] Pb with a simple pointer allocation

Dear Pascal and Frama-C users,
>> /*@ lemma is_peraps_needed :
>> @ \forall integer m, n; 0<m ==> 0<n ==> n<(m*n);
>> @*/
> Patrick Baudin pointed out to me at lunchbreak that this property is
> false for m=n=1.
Thanks Pascal ! (forget this easy case). But the program still 
unprovable. Is it due to the use of two pointers on the same aera of 
memory ? Note that when (m==1 or m==2 or n==1 or n==2) in the 
"requieres", there is no pb. Is it due to a lack of axiom for the 
"shift(ppd, 0)" genereted for the only lemma that still have no solution 
for provers ?

#include <limits.h>

#define SZDBL (sizeof(double))

requires m>0 && n>0 && m*n*SZDBL<LONG_MAX;
double **matallocd(int m, int n){
   double *pd, **ppd;    ppd= (double **)malloc(m*sizeof(double *));
   pd= (double *)malloc(m*n*SZDBL);
   /*@ assert \valid_range(ppd[0],0,n-1); */