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/*
* ibuild : build a fast linear interpolation table
*
* ibuild is designed to read in a list of x and f(x) values and then build
* a table that can be used to interpolate f(x) values more quickly. It does
* this by precomputing the equation of the line associated with each
* interval in the table. These equations are output as C initialized
* structures that can be passed to interpolate() for processing.
*
* Author: Riley Rainey riley@mips.com
*
*/
#include <stdio.h>
#include <interpolate.h>
main (argc, argv)
int argc;
char *argv[]; {
float x[256], y[256];
int count, i;
ITable table;
IEntry entry[256];
FILE *f;
if ((f = fopen(argv[1], "r")) == (FILE *) NULL) {
perror ("can't open input file");
exit (1);
}
fscanf (f, "%d", &count);
fscanf (f, "%f%f", &x[0], &y[0]);
table.minX = x[0];
table.count = count-1;
printf ("\n/* This interpolation table was built by ibuild */\n\n");
printf ("static IEntry %s_e[] = {\n", argv[1]);
for (i=1; i<count; ++i) {
fscanf (f, "%f%f", &x[i], &y[i]);
entry[i-1].m = (y[i] - y[i-1]) / (x[i] - x[i-1]);
entry[i-1].b = y[i] - (x[i] * entry[i-1].m);
printf ("\t{\t%g,\t%g,\t%g },\n", (double) x[i],
(double) entry[i-1].m, (double) entry[i-1].b);
}
printf ("\t};\n");
printf ("static ITable %s = { %d, %g, %s_e };\n", argv[1],
table.count, (double) table.minX, argv[1]);
exit (0);
}
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