gdmag.f
54 lines
| 1.5 KiB
| text/x-fortran
|
FortranFixedLexer
| r0 | C $Id: gdmag.f 3304 2011-01-17 15:25:59Z brideout $ | |||
| C | ||||
| SUBROUTINE GDMAG(TM,GDLAT,GLON,GDALT,X,Y,Z,F,H,DEC,AINC) | ||||
| C | ||||
| C jmh - 1/80 ans fortran 66 | ||||
| C | ||||
| C Evaluates the geomagnetic field at a point specified by its | ||||
| C geodetic coordinates. the reference geoid is that adopted by the | ||||
| C iau in 1964. | ||||
| C | ||||
| C input: | ||||
| C TM - time in years for desired field (e.g. 1971.25) | ||||
| C GDLAT - geodetic latitude (degrees) | ||||
| C GLON - east longitude (degrees) | ||||
| C GDALT - altitude above geoid (km) | ||||
| C | ||||
| C output: | ||||
| C X,Y,Z - geodetic field components (gauss) | ||||
| C F - magnitude of field (gauss) | ||||
| C H - horizontal intensity (gauss) | ||||
| C DEC - declination (degrees) | ||||
| C AINC - inclination (degrees) | ||||
| C | ||||
| C .. Scalar Arguments .. | ||||
| DOUBLE PRECISION AINC,DEC,F,GDALT,GDLAT,GLON,H,TM,X,Y,Z | ||||
| C .. | ||||
| C .. Local Scalars .. | ||||
| DOUBLE PRECISION BP,BR,BT,CP,CT,DTR,GCLAT,P,RKM,SP,ST,T | ||||
| C .. | ||||
| C .. External Subroutines .. | ||||
| EXTERNAL CONVRT,GDV,MILMAG | ||||
| C .. | ||||
| C .. Intrinsic Functions .. | ||||
| INTRINSIC DATAN2,DCOS,DSIN,DSQRT | ||||
| C .. | ||||
| C .. Data statements .. | ||||
| DATA DTR/.0174532925199D0/ | ||||
| C .. | ||||
| C | ||||
| CALL CONVRT(1,GDLAT,GDALT,GCLAT,RKM) | ||||
| T = DTR*(90.D0-GCLAT) | ||||
| CT = DCOS(T) | ||||
| ST = DSIN(T) | ||||
| P = DTR*GLON | ||||
| CP = DCOS(P) | ||||
| SP = DSIN(P) | ||||
| CALL MILMAG(TM,RKM,ST,CT,SP,CP,BR,BT,BP,F) | ||||
| CALL GDV(GDLAT,GCLAT,BR,BT,BP,X,Y,Z) | ||||
| H = DSQRT(X*X+Y*Y) | ||||
| DEC = DATAN2(Y,X)/DTR | ||||
| AINC = DATAN2(Z,H)/DTR | ||||
| RETURN | ||||
| C | ||||
| END | ||||
