#include    <stdio.h>

main(int argc, char *argv[])
{   char str; int m=0; double year=0.;
    double latd, latf, lond, lonf, alt, f, fm[6];
    fprintf(stderr, "\nCalculate IGRF components\n\n");
    while ((m<1) || (m>3))
        gparmi("Select model - DGRF (1), PGRF (2) or IGRF (3)  ==> ", &m);
    while ((year<1900.) || (year>2005.))
        gparmd("Select the YEAR of calculation  ==> ", &year);
    if (m == 1) { dgrfs(year); str = 'D'; }
    else if (m == 2) { pgrfs(year); str = 'P'; }
    else { igrfs(year); str = 'I'; }
    printf("\n%cGRF in %7.2f\n", str,year);
    while (1) {
        latd = 99999.; latf = 0.; lond = 0.; lonf = 0.; alt = 0.;
        prompt("\n  Latitude ?  (deg. min.)\n");
        gparmd2("   < Hit RETURN to Quit > ==> ", &latd,&latf);
        if (latd == 99999.) { fputc('\n',stderr); break; }
        gparmd2("  Longitude ? (deg. min.) ==> ", &lond,&lonf);
        gparmd("  Altitude ?  (in meters) ==> ", &alt);
        latd = latd+latf/60.; lond = lond+lonf/60.;
        igrfc(latd, lond, alt, &f); igrfm(fm);
        printf("%7.3f N %8.3f E %6.0f m  :  F =%8.1f  H =%8.3f  Z =%8.3f\n",
                latd, lond, alt, f, fm[3], fm[2]);
        printf("                              dip =%8.3f   dec =%8.3f\n",
                fm[4], fm[5]);
    }
}