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/*****************************************************************************
* Johns Hopkins University
* Center For Astrophysical Sciences
* FUSE
*****************************************************************************
*
* Synopsis: getshift spec1 spec2 w1 w2
*
* Description: Computes the wavelength shift between the spectra from two
* different exposures spec1 and spec2 using a cross-correlation
* in the wavelength window defined by w1 and w2
*
*
* History: 01/08/04 bjg 1.0 begin work
* 04/05/04 bjg 1.1 Return EXIT_SUCCESS
* Correct formats to match
* argument types in printf
* 08/26/05 wvd 1.2 If given no arguments, don't return error.
* Just print message and exit.
*
****************************************************************************/
#include <time.h>
#include <math.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include "calfuse.h"
#define MAXSHIFT 25
#define SMOOTH_PAR 4
static char CF_PRGM_ID[] = "get_shift";
static char CF_VER_NUM[] = "1.2";
int wave_search(float *table, int i, int j, float elmt){
int k;
if (i>=j) return i;
if (elmt==table[i]) return i;
if (elmt==table[j]) return j;
k=(i+j)/2;
if (elmt==table[k]) return k;
if ((elmt-table[i])*(elmt-table[k])<0) return wave_search(table,i,k,elmt);
return wave_search(table,k+1,j,elmt);
}
int main(int argc, char *argv[])
{
int status=0;
int hdutype=0;
long n,n1,n2,laux,i,j,k;
float *wave, *flux1, *flux2, *flux1s, *flux2s;
float w1,w2;
fitsfile *infits1, *infits2;
float correl[2*MAXSHIFT+1];
/* Enter a timestamp into the log. */
cf_timestamp(CF_PRGM_ID, CF_VER_NUM, "Begin Processing");
/* Initialize error checking */
cf_error_init(CF_PRGM_ID, CF_VER_NUM, stderr);
/* check command line */
if (argc != 5) {
printf("Usage: getshift spec1 spec2 w1 w2 \n");
return 1;
}
FITS_open_file(&infits1, argv[1], READONLY, &status);
FITS_open_file(&infits2, argv[2], READONLY, &status);
sscanf(argv[3],"%f",&w1);
sscanf(argv[4],"%f",&w2);
FITS_movabs_hdu(infits1, 2, &hdutype, &status);
FITS_movabs_hdu(infits2, 2, &hdutype, &status);
n=cf_read_col(infits1,TFLOAT,"WAVE",(void **) &wave);
n=cf_read_col(infits1,TFLOAT,"FLUX",(void **) &flux1);
n=cf_read_col(infits2,TFLOAT,"FLUX",(void **) &flux2);
flux1s=(float*)malloc(n*sizeof(float));
flux2s=(float*)malloc(n*sizeof(float));
for (i=0;i<n;i++){
flux1s[i]=0;
flux2s[i]=0;
k=0;
for (j=i-SMOOTH_PAR;j<=i+SMOOTH_PAR;j++){
if ((j>=0)&&(j<n)) {
flux1s[i]+=flux1[j];
flux2s[i]+=flux2[j];
k=k+1;
}
}
flux1s[i]/=k;
flux2s[i]/=k;
}
if ((w1-wave[0])*(w1-wave[n-1])>0)
cf_if_error("Wavelength parameters out of range\n");
if ((w2-wave[0])*(w2-wave[n-1])>0)
cf_if_error("Wavelength parameters out of range\n");
n1=wave_search(wave,0,n-1,w1);
n2=wave_search(wave,0,n-1,w2);
if (n1>n2) {
laux=n2;
n2=n1;
n1=laux;
}
if ((n1-MAXSHIFT<0)||(n2+MAXSHIFT>=n))
cf_if_error("Wavelength parameters too close to bounds\n");
k=0;
for (i=0;i<=2*MAXSHIFT;i++){
correl[i]=0;
for (j=n1;j<=n2;j++){
correl[i]=correl[i]+flux1s[j]*flux2s[j+i-MAXSHIFT];
}
if (correl[i]>correl[k]) k=i;
}
FITS_close_file(infits1, &status);
FITS_close_file(infits2, &status);
/* Enter a timestamp into the log. */
cf_timestamp(CF_PRGM_ID, CF_VER_NUM, "Done processing");
printf("Shift is %ld steps.\n",k-MAXSHIFT);
return EXIT_SUCCESS;
}
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