int IGRFCall(double date, double flat, double flon,
double elev, double *x, double *y, double *z) {
int i;
char *envstr;
char file1[256];
char file2[256];
double ext[3]={0.0,0.0,0.0};
double a2 = 40680925.0;
double b2 = 40408588.0;
if (igrf_date !=date) {
for (i=0;(dtemod[i] !=0) && (dtemod[i]<date);i++);
if (i==0) return -1;
i--;
igrf_date=date;
envstr=getenv("IGRF_PATH");
sprintf(file1,"%s/%s",envstr,filmod[i]);
getshc(file1, &nmax1, &erad, gh1);
sprintf(file2,"%s/%s",envstr,filmod[i+1]);
getshc(file2, &nmax2, &erad, gh2);
if (i < 12) {
interpshc(date, dtemod[i],
nmax1, gh1, dtemod[i+1], nmax2, gh2, &nmax, gha);
interpshc(date+1,dtemod[i],
nmax1, gh1, dtemod[i+1], nmax2, gh2, &nmax, ghb);
} else {
extrapshc(date, dtemod[i],
nmax1, gh1, nmax2, gh2, &nmax, gha);
extrapshc(date+1,dtemod[i],
nmax1, gh1, nmax2, gh2, &nmax, ghb);
}
}
shval3(1, flat, flon, elev, erad, a2, b2, nmax, gha, 0,
ext, x, y, z);
return 0;
}
int IGRFCall(double date, double flat, double flon,
double elev, double *x, double *y, double *z) {
int i;
char *envstr;
char file1[256];
char file2[256];
char line[256];
FILE *fp;
double ext[3]={0.0,0.0,0.0};
double a2 = 40680925.0;
double b2 = 40408588.0;
if (dtemax==0) {
envstr=getenv("IGRF_PATH");
sprintf(file1,"%s/%s",envstr,"coef.dat");
fp=fopen(file1,"r");
if (fp==NULL) return -1;
int i=0;
while (fgets(line,255,fp) !=NULL) {
sscanf(line,"%s %lf",filmod[i],&dtemod[i]);
i++;
}
dtemod[i]=0;
dtemax=i-2;
fclose(fp);
}
if (igrf_date !=date) {
for (i=0;(dtemod[i] !=0) && (dtemod[i]<date);i++);
if (i==0) return -1;
i--;
igrf_date=date;
envstr=getenv("IGRF_PATH");
sprintf(file1,"%s/%s",envstr,filmod[i]);
getshc(file1, &nmax1, &erad, gh1);
sprintf(file2,"%s/%s",envstr,filmod[i+1]);
getshc(file2, &nmax2, &erad, gh2);
if (i < dtemax) {
interpshc(date, dtemod[i],
nmax1, gh1, dtemod[i+1], nmax2, gh2, &nmax, gha);
interpshc(date+1,dtemod[i],
nmax1, gh1, dtemod[i+1], nmax2, gh2, &nmax, ghb);
} else {
extrapshc(date, dtemod[i],
nmax1, gh1, nmax2, gh2, &nmax, gha);
extrapshc(date+1,dtemod[i],
nmax1, gh1, nmax2, gh2, &nmax, ghb);
}
}
shval3(2, flat, flon, elev, erad, a2, b2, nmax, gha, 0,
ext, x, y, z);
return 0;
}
