Code Snippets Submitted by Slartibartfast
Taylor-Weighted Window Generator
/*
11/8/89 Eric Jacobsen
Generates Taylor weighting coefficients for a vector
of arbitrary length n. The user supplies n' (nprime),
the number of terms used in the calculations, and A,
the peak sidelobe ratio in db. N must also be supplied
by the user.
This version (HTaylor) scales the output data by a
user supplied integer. The output is rounded to the
nearest integer.
*/
#include <stdio.h>
#include <math.h>
void main(argc,argv)
int argc;
char *argv[];
{
char outfile[30],
*help="\n USE: Taylor outfile N A n' s\n\n © 11/89 Eric Jacobsen\n\n N = # pts, A = PSLR, n' = # terms, s = integer scale factor.\n\n";
float Fm,k,sigma,x,A,dprod,nprod,scl;
int i,m,N,nprime,p,scale,*w,*h;
extern double cos(),log(),pow();
FILE *fopen(),*fp;
if(argv[1][0]=='?'){
puts(help);
exit(0);
}
if(argc<2){
printf("\n Enter name of output file: ");
scanf("%s",outfile);
}
else strcpy(outfile,argv[1]);
if(argc<3){
printf("\n Enter the number of points: ");
scanf("%d",&N);
}
else N=atoi(argv[2]);
if(argc<4){
printf("\n Enter PSLR (A) in db: ");
scanf("%f",&A);
}
else A=atof(argv[3]);
A=abs(A);
if(argc<5){
printf("\n Enter the number of terms (n'): ");
scanf("%d",&nprime);
}
else nprime=atoi(argv[4]);
if(argc<6){
printf("\n Enter the scale factor: ");
scanf("%d",&scale);
}
else scale=atoi(argv[5]);
if(!(fp=fopen(outfile,"w"))){
printf("\n\n Can't open %s.\n\n",outfile);
exit(2);
}
k=0.885*(1.0+((A-13.0)/65.0));
x=pow(10.0,A/20.0);
A=log(x+sqrt((x*x)-1))/PI;
sigma=(float)nprime/sqrt((A*A)+(((float)nprime)-0.5)*(((float)nprime)-0.5));
printf("\n Sigma = %f, k = %f\n\n Calculating...",sigma,k);
Fm=0.0;
for(m=1;m<nprime;m++){
dprod=nprod=1.0;
for(p=1;p<nprime;p++){
if(p!=m)dprod*=1.0-((float)(m*m)/(float)(p*p));
nprod*=1.0-(float)(m*m)/(((A*A)+(((float)p)-0.5)*(((float)p)-0.5))*sigma*sigma);
}
Fm+=(float)(m % 2 ? 1:-1)*nprod/dprod;
}
if(!(w=h=(int *)AllocMem(4*N,0))){
puts("\n\n ** Insufficient Memory **\n\n");
exit(12);
}
scl=(float)scale;
for(i=0;i<N;i++)
*w++=(int)(scl*(1.0+(Fm*(-cos(2.0*PI*(float)i/(float)N))))+0.5);
printf("done.\n");
printf("\n Writing output file...");
w=h;
for(i=0;i<N;i++)fprintf(fp," DC.W %d\n",*w++);
printf("done.\n\n");
FreeMem(h,4*N);
fclose(fp);
}
Taylor-Weighted Window Generator
/*
11/8/89 Eric Jacobsen
Generates Taylor weighting coefficients for a vector
of arbitrary length n. The user supplies n' (nprime),
the number of terms used in the calculations, and A,
the peak sidelobe ratio in db. N must also be supplied
by the user.
This version (HTaylor) scales the output data by a
user supplied integer. The output is rounded to the
nearest integer.
*/
#include <stdio.h>
#include <math.h>
void main(argc,argv)
int argc;
char *argv[];
{
char outfile[30],
*help="\n USE: Taylor outfile N A n' s\n\n © 11/89 Eric Jacobsen\n\n N = # pts, A = PSLR, n' = # terms, s = integer scale factor.\n\n";
float Fm,k,sigma,x,A,dprod,nprod,scl;
int i,m,N,nprime,p,scale,*w,*h;
extern double cos(),log(),pow();
FILE *fopen(),*fp;
if(argv[1][0]=='?'){
puts(help);
exit(0);
}
if(argc<2){
printf("\n Enter name of output file: ");
scanf("%s",outfile);
}
else strcpy(outfile,argv[1]);
if(argc<3){
printf("\n Enter the number of points: ");
scanf("%d",&N);
}
else N=atoi(argv[2]);
if(argc<4){
printf("\n Enter PSLR (A) in db: ");
scanf("%f",&A);
}
else A=atof(argv[3]);
A=abs(A);
if(argc<5){
printf("\n Enter the number of terms (n'): ");
scanf("%d",&nprime);
}
else nprime=atoi(argv[4]);
if(argc<6){
printf("\n Enter the scale factor: ");
scanf("%d",&scale);
}
else scale=atoi(argv[5]);
if(!(fp=fopen(outfile,"w"))){
printf("\n\n Can't open %s.\n\n",outfile);
exit(2);
}
k=0.885*(1.0+((A-13.0)/65.0));
x=pow(10.0,A/20.0);
A=log(x+sqrt((x*x)-1))/PI;
sigma=(float)nprime/sqrt((A*A)+(((float)nprime)-0.5)*(((float)nprime)-0.5));
printf("\n Sigma = %f, k = %f\n\n Calculating...",sigma,k);
Fm=0.0;
for(m=1;m<nprime;m++){
dprod=nprod=1.0;
for(p=1;p<nprime;p++){
if(p!=m)dprod*=1.0-((float)(m*m)/(float)(p*p));
nprod*=1.0-(float)(m*m)/(((A*A)+(((float)p)-0.5)*(((float)p)-0.5))*sigma*sigma);
}
Fm+=(float)(m % 2 ? 1:-1)*nprod/dprod;
}
if(!(w=h=(int *)AllocMem(4*N,0))){
puts("\n\n ** Insufficient Memory **\n\n");
exit(12);
}
scl=(float)scale;
for(i=0;i<N;i++)
*w++=(int)(scl*(1.0+(Fm*(-cos(2.0*PI*(float)i/(float)N))))+0.5);
printf("done.\n");
printf("\n Writing output file...");
w=h;
for(i=0;i<N;i++)fprintf(fp," DC.W %d\n",*w++);
printf("done.\n\n");
FreeMem(h,4*N);
fclose(fp);
}