#include    <stdio.h>
#include    <stdlib.h>
#include    <string.h>

void opnpinc(int argc, char *argv[]);
int premsg(char *str);
void gparma(char *str, int lnam, char *nam);
int prompt(char *str);
void gparmd2(char *str, double *dv1, double *dv2);
void clspin();
int sgeoid(char *model);
int hgeoid(double flat, double flon, double *hh);

int main(int argc, char *argv[])
{   int ido, kdo;
    double latd, latf, latm, lond, lonf, lonm, gi, gk, hg;
    char model[21], cns, cew;
    opnpinc(argc, argv);
    premsg("\nCalc. Geoid height\n");
    premsg("Select Geoid model: ");
    premsg("  0:NGA (within 20-50N, 120-150E)");
    premsg("   or others [Enter NAME]");
    gparma("  (NGA-world 10'x15' mesh may be selected by '.') ==> ",
           20, model);
    if (strcmp(model,"0") == 0) strcpy(model, "NGA");
    premsg("");
    if (sgeoid(model) < 0) exit(1);
    premsg(" Enter Latitude and Longitude in WGS coord.\n\n");
    while (1) {
        latd = 99999.; latf = 0.; lond = 0.; lonf = 0.;
        prompt("  Latitude ?  [deg. min.]\n");
        gparmd2("   < Hit RETURN to Quit > ==> ", &latd,&latf);
        if (latd == 99999.) { fputc('\n',stderr); break; }
        gparmd2("  Longitude ? [deg. min.] ==> ", &lond,&lonf);
        gi = latd*60.+latf; gk = lond*60.+lonf;
        if (gi < 0.) { cns = 'S'; gi = -gi; } else cns = 'N';
        if (gk < 0.) { cew = 'W'; gk = -gk; } else cew = 'E';
        ido = (int)(gi/60.); latm = gi - ido*60.;
        kdo = (int)(gk/60.); lonm = gk - kdo*60.;
        printf("  %3d: %6.3f\' %c  %3d: %6.3f\' %c  WGS  :",
               ido, latm, cns, kdo, lonm, cew);
        if (hgeoid(latf, lonf, &hg) < 0) {
            printf("   unknown\n");
        } else {
            printf("  hgeoid = %6.3f m\n\n", hg);
        }
    }
    clspin();
    return(0);
}