hello all,
I am stuck and am unable to proceed anywhere on account of segmentation fault in the following code...can anyone temme what im doing wrong and how to rectify it.any help will be welcome

Code:
#include<stdio.h>
#include<math.h>
#include<stdlib.h>


//Signum function
int sig(float a)
{
if (a>=0)
return 1 ;
else return -1;
}
//Function to return absolute value
/*double abs (double a)
{
if (a>=0)
return a;
else return -1*a;
}
*/
void main()

{
     int *b,l=3000,k,i;
    double a[3000],**c;
 
    if (c==NULL)
            {
              printf("error...""no memory left");
              exit(0);
            }
    



for(k=0;k<3000;k++)
{ a[k]=-k+0.6*k*0.6*k-0.36*k*k*k;
}
b=&l;

        for ( k=0;k<15;k++)
         
            {
              c[k]=(double *)malloc(*b/15 * sizeof(double));
                      
         
          if (c[k]==NULL)
                {
                      printf("error...""no memory left");
                      exit(0);
                }

            }           



double **denoising(double *arr,int *arrsize)
    {     
     int count=0,window[300],z_mean=0,stdev=0,start,stop,num=100,k,j;
     int *z_crossings=NULL;     
     double  thresh,temp[300],emean=0,**templ=NULL;
     double *energyframe=NULL;  
         
         
    // a block of memory is allocated to the pointer templ which is used to keep track of each template and contain its values
    templ=(double**)malloc(15*sizeof(double));
        
      
    if (templ==NULL)
            {
              printf("error...""no memory left");
              exit(0);
            }
    
        for ( k=0;k<15;k++)
         
            {
              templ[k]=(double *)malloc(*arrsize/15 * sizeof(double));
                      
         
          if (templ[k]==NULL)
                {
                      printf("error...""no memory left");
                      exit(0);
                }

            }    
    
    /*Initialises a rectangular window of size 300//
    for (i=0;i<300;i++)
     { 
       window[i]=1;
     }
     */    
      start=0;
      stop=300;
         
     z_crossings= (int *)malloc((*arrsize-stop+1)*sizeof(int));
        
      if (z_crossings==NULL)
            {
              printf("error...""no memory left");
              exit(0);
            }
     
         energyframe=(double *)malloc((*arrsize-stop+1)*sizeof(double));
        
     if (energyframe==NULL)
            {
              printf("error...""no memory left");
              exit(0);
            }






      while(stop < *arrsize)
     {    
      energyframe[count]=0;
          z_crossings[count]=0;       
    
     
       for (j=start;j<stop;j++)
         {   
        
          //temp[j]=arr[j]*window[j-start];
            temp[j-start]=arr[j];
          //Computes energy in each frame//
          energyframe[count]+=temp[j-start]*temp[j-start];
              //Coomputes zero crossingsin each frame//
              z_crossings[count]+= 1/2*(abs(sig(temp[j-start+1])-sig(temp[j-start])));        
         }    
         
       start++;
           stop++;
           count++;   
     }
     
for( j=0;j<count;j++)
 {
 emean +=energyframe[j]/count;
 //z_mean +=z_crossings[j]/count;//
 }
/*for( j=0;j<count;j++)
 { 
  stdev+=((z_mean-z_crossings[j])^2)/count;
 }
*/

//The mean of the energy in each frame is set as the threshold
thresh=emean;
//The threshold for zero crossings is set// 
//num=z_mean + 3*sqrt(stdev);

j=0;
count=0;

do
    { 
        if ((energyframe[j]>=thresh) && (z_crossings[j]<=num))
            { start=j ;
                while((energyframe[j]>=thresh) && (z_crossings[j]<=num))
                {
                    j++;
                }
             stop=j-1;
             for (i=start;i<=stop;i++)
                {
                 templ[count][i-start]=arr[i];//Records each signal frame(denoised) in a template//
                }
                         count++ ;
               }
        else j++;
        
    }while(j<*arrsize);

  free(z_crossings);
  free(energyframe);
  z_crossings=NULL;
   energyframe=NULL;

return templ;
free(templ);
}
c=denoising(a,b);
int j=0;
while(c!=NULL)
{ j=0;
  while(c[j]!=NULL)
  { 
   printf("%f",*c[j]);
    j++;
   }

}
free(c);
}

Last edited by shabbir; 10Sep2011 at 19:10.. Reason: Code blocks