xmax.c

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#include <stdlib.h>
 
#include <grass/gis.h>
#include <grass/raster.h>
#include <grass/calc.h>
 
/****************************************************************
max(x0,x1,...,xn) returns maximum value
****************************************************************/
 
int f_max(int argc, const int *argt, void **args)
{
    int i, j;
 
    if (argc < 1)
        return E_ARG_LO;
 
    for (i = 1; i <= argc; i++)
        if (argt[i] != argt[0])
            return E_ARG_TYPE;
 
    switch (argt[0]) {
    case CELL_TYPE: {
        CELL *res = args[0];
        CELL **argz = (CELL **)args;
 
        for (i = 0; i < columns; i++) {
            int nul = 0;
            CELL max;
 
            for (j = 1; j <= argc; j++)
                if (IS_NULL_C(&argz[j][i]))
                    nul = 1;
                else if (j == 1)
                    max = argz[j][i];
                else if (max < argz[j][i])
                    max = argz[j][i];
            if (nul)
                SET_NULL_C(&res[i]);
            else
                res[i] = max;
        }
        return 0;
    }
    case FCELL_TYPE: {
        FCELL *res = args[0];
        FCELL **argz = (FCELL **)args;
 
        for (i = 0; i < columns; i++) {
            int nul = 0;
            FCELL max;
 
            for (j = 1; j <= argc; j++)
                if (IS_NULL_F(&argz[j][i]))
                    nul = 1;
                else if (j == 1)
                    max = argz[j][i];
                else if (max < argz[j][i])
                    max = argz[j][i];
            if (nul)
                SET_NULL_F(&res[i]);
            else
                res[i] = max;
        }
 
        return 0;
    }
    case DCELL_TYPE: {
        DCELL *res = args[0];
        DCELL **argz = (DCELL **)args;
 
        for (i = 0; i < columns; i++) {
            int nul = 0;
            DCELL max;
 
            for (j = 1; j <= argc; j++)
                if (IS_NULL_D(&argz[j][i]))
                    nul = 1;
                else if (j == 1)
                    max = argz[j][i];
                else if (max < argz[j][i])
                    max = argz[j][i];
            if (nul)
                SET_NULL_D(&res[i]);
            else
                res[i] = max;
        }
 
        return 0;
    }
    default:
        return E_INV_TYPE;
    }
}