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+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "fitsio.h"
+
+/*
+ This program illustrates how to use the CFITSIO iterator function.
+ It reads and modifies the input 'iter_a.fit' file by computing a
+ value for the 'rate' column as a function of the values in the other
+ 'counts' and 'time' columns.
+*/
+main()
+{
+ extern flux_rate(); /* external work function is passed to the iterator */
+ fitsfile *fptr;
+ iteratorCol cols[3]; /* structure used by the iterator function */
+ int n_cols;
+ long rows_per_loop, offset;
+
+ int status, nkeys, keypos, hdutype, ii, jj;
+ char filename[] = "vari.fits"; /* name of rate FITS file */
+
+ status = 0;
+
+ fits_open_file(&fptr, filename, READWRITE, &status); /* open file */
+
+ /* move to the desired binary table extension */
+ if (fits_movnam_hdu(fptr, BINARY_TBL, "COMPRESSED_IMAGE", 0, &status) )
+ fits_report_error(stderr, status); /* print out error messages */
+
+ n_cols = 1; /* number of columns */
+
+ /* define input column structure members for the iterator function */
+ fits_iter_set_by_name(&cols[0], fptr, "COMPRESSED_DATA", 0, InputCol);
+
+ rows_per_loop = 0; /* use default optimum number of rows */
+ offset = 0; /* process all the rows */
+
+ /* apply the rate function to each row of the table */
+ printf("Calling iterator function...%d\n", status);
+
+ fits_iterate_data(n_cols, cols, offset, rows_per_loop,
+ flux_rate, 0L, &status);
+
+ fits_close_file(fptr, &status); /* all done */
+
+ if (status)
+ fits_report_error(stderr, status); /* print out error messages */
+
+ return(status);
+}
+/*--------------------------------------------------------------------------*/
+int flux_rate(long totalrows, long offset, long firstrow, long nrows,
+ int ncols, iteratorCol *cols, void *user_strct )
+
+/*
+ Sample iterator function that calculates the output flux 'rate' column
+ by dividing the input 'counts' by the 'time' column.
+ It also applies a constant deadtime correction factor if the 'deadtime'
+ keyword exists. Finally, this creates or updates the 'LIVETIME'
+ keyword with the sum of all the individual integration times.
+*/
+{
+ int ii, status = 0;
+ long repeat;
+
+ /* declare variables static to preserve their values between calls */
+ static unsigned char *counts;
+
+ /*--------------------------------------------------------*/
+ /* Initialization procedures: execute on the first call */
+ /*--------------------------------------------------------*/
+ if (firstrow == 1)
+ {
+
+printf("Datatype of column = %d\n",fits_iter_get_datatype(&cols[0]));
+
+ /* assign the input pointers to the appropriate arrays and null ptrs*/
+ counts = (long *) fits_iter_get_array(&cols[0]);
+
+ }
+
+ /*--------------------------------------------*/
+ /* Main loop: process all the rows of data */
+ /*--------------------------------------------*/
+
+ /* NOTE: 1st element of array is the null pixel value! */
+ /* Loop from 1 to nrows, not 0 to nrows - 1. */
+
+
+ for (ii = 1; ii <= nrows; ii++)
+ {
+ repeat = fits_iter_get_repeat(&cols[0]);
+ printf ("repeat = %d, %d\n",repeat, counts[1]);
+
+ }
+
+
+ return(0); /* return successful status */
+}