/* to smooth a time serial by padding zero at high frequencies;
 * resample is done such that dt<=maxdt;
 */
 
#include <stdlib.h>

int min2n();

float *smooth(data1,n1,dt1,maxdt,n2,dt2)
float *data1,maxdt,dt1,*dt2;
int n1,*n2;
{
static int mn=0;
int m,i,n;
static float *data2;
	
	*dt2=dt1;
	*n2=n1;
	while(*dt2>maxdt)
	{ *dt2/=2.;
	  *n2*=2;
	}
	
	m=min2n(*n2);
	
	if(mn<m+2)
	{ if(mn) free(data2);
	  mn=m+2;
	  data2=(float *)malloc(sizeof(float)*mn);
	}
	
	for(i=0;i<n1;i++) data2[i]=data1[i];
	
	if(*n2>n1)
	{ float fac;
	  n=min2n(n1);
	  for(i=n1;i<n;i++) data2[i]=0.;
	  cfftr(data2,n);
	/*  for(i=n;i<m+2;i++) data2[i]=0.;*/
	  for(i=n+2;i<m+2;i++) data2[i]=0.;
	  	  
	  cfftri(data2,m);
	  fac=(float)(n/2);
	  for(i=0;i<*n2;i++) data2[i]/=fac;
	}
	
	return(data2);
	
}