xrand.c

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#include <stdlib.h>
 
#include <grass/config.h>
#include <grass/gis.h>
#include <grass/raster.h>
#include <grass/calc.h>
 
/****************************************************************
rand(lo,hi) random values between a and b
****************************************************************/
 
int f_rand(int argc, const int *argt, void **args)
{
    int i;
 
    if (argc < 2)
        return E_ARG_LO;
    if (argc > 2)
        return E_ARG_HI;
 
    switch (argt[0]) {
    case CELL_TYPE: {
        CELL *res = args[0];
        CELL *arg1 = args[1];
        CELL *arg2 = args[2];
 
        for (i = 0; i < columns; i++) {
            unsigned int x = (unsigned int)G_mrand48();
            int lo = arg1[i];
            int hi = arg2[i];
 
            if (lo > hi) {
                int tmp = lo;
 
                lo = hi;
                hi = tmp;
            }
            res[i] = (lo == hi) ? lo : (int)(lo + x % (unsigned int)(hi - lo));
        }
        return 0;
    }
    case FCELL_TYPE: {
        FCELL *res = args[0];
        FCELL *arg1 = args[1];
        FCELL *arg2 = args[2];
 
        for (i = 0; i < columns; i++) {
            double x = G_drand48();
            FCELL lo = arg1[i];
            FCELL hi = arg2[i];
 
            if (lo > hi) {
                FCELL tmp = lo;
 
                lo = hi;
                hi = tmp;
            }
            res[i] = (FCELL)(lo + x * (hi - lo));
        }
        return 0;
    }
    case DCELL_TYPE: {
        DCELL *res = args[0];
        DCELL *arg1 = args[1];
        DCELL *arg2 = args[2];
 
        for (i = 0; i < columns; i++) {
            double x = G_drand48();
            DCELL lo = arg1[i];
            DCELL hi = arg2[i];
 
            if (lo > hi) {
                DCELL tmp = lo;
 
                lo = hi;
                hi = tmp;
            }
            res[i] = lo + x * (hi - lo);
        }
        return 0;
    }
    default:
        return E_INV_TYPE;
    }
}