SUBROUTINE INTVAG%FO,ALO,GO,VA,VO,R< INTG 2 C FO IS LAT IN DEGREES,ALO LONGITUDE IN DEGREES OF DESIRED POINT INTG 3 C GO GRAVITY IN GALS,VA VARIANCE OF GO,VO UNIT VAR APPROX 1 INTG 4 C G OBSERVED GRAVITY IN GALS WITH FREE AIR CORRECTION INTG 5 C S VARIANCE OF G IN GALS L ELEVATION FACTOR INTG 6 C N NUMBER OF POINTS SELECTED FOR INTERPOLATION INTG 7 DIMENSION F%4000<,AL%4000<,G%4000<,S%4000< INTG 8 DIMENSION BLOCK%4,1000<,IBLOCK%8004< INTG 9 C BLOCK,IBLOCK WRITTEN OUT AND READ IN ON UNIT IG INTG 10 DIMENSION GR%50<,X%50<,Y%50<,W%50< INTG 11 C X,Y CARTESIAN COORDS OF GRAVITY POINTS INTG 12 C GR VALUES OF GRAVITY AT THESE POINTS WITH FREE AIR CORRECTION INTG 13 C W WEIGHTS FOR EACH POINT FOR USE WITH INTERPOLATION INTG 14 EQUIVALENCE %IBLOCK%3<,BLOCK%1,1<< INTG 15 C IBLOCK%1< CONTAINS DEGSQ INTG 16 C IBLOCK%2< CONTAINS NUMBER OF USABLE WORDS INTG 17 C ENSURES FIRST WORD IN IBLOCK IS SENTINEL#DEGSQUARE INTG 18 EQUIVALENCE %BLOCK%1,1<,F%1<<,%BLOCK%2,1<,AL%1<< INTG 19 C LAT LONG ARE ROWS 1 AND 2 OF BLOCK INTG 20 EQUIVALENCE %BLOCK%3,1<,G%1<<,%BLOCK%4,1<,S%1<< INTG 21 C ROWS 3 AND 4 OF BLOCK ARE GRAVITY AND ITS VARIANCE INTG 22 DIMENSION AA%50,9<,CC%9<,DD%10,10<,V%9<,IQUART%4< INTG 23 DIMENSION IQ%4< INTG 24 C IQUART INDICATES IF POINTS IN EACH QUADRANT%GT,#1< OR NOT %#0< OF INTG 25 C IQ INDICATES IF POINTS IN EACH QUAD OF INNER CIRCLE INTG 26 COMMON IBLOCK INTGB 1 DATA LLCSX/0/,IG/20/,IPR/3/ INTG 27 C IG UNIT NO OF BLOCKED FILE OF INPUT DATA INTG 28 C INITIALLY ILLCSX SET TO ZERO TO FORCE READING INTG 29 DATA PI180/.017453289/ INTG 30 C PI180 IS PI/180 DEGREES TO RADIANS INTG 31 LLCS#INT%FO<*1000&INT%ALO< INTG 32 C COMPUTE DEGREE SQUARE REQUESTED BY FO,ALO INTG 33 IF%LLCS .EQ. LLCSX< GO TO 10 INTG 34 C CHECK IF PREVIOUS DATA CAN STILL BE USED INTG 35 LLBS#LLCS-1001 INTG 36 C LLBS IS FIRST OF 9 DEGREE SQUARES TO BE READ INTG 37 REWIND IG INTGA 1 C REWIND UNIT WITH BLOCKED GRAVITY DATA INTG 39 NTW#3 INTG 40 DO 30 I#1,3 INTG 41 DO 31 J#1,3 INTG 42 C READ IN 9 DEGREE SQUARES INTG 43 ISEAR#LLBS&J-1&%I-1<*1000 INTG 44 C ISEAR IS DEGREE SQUARE TO BE USED IN THE SEARCH INTG 45 ISTORA #IBLOCK%NTW-1< INTG 46 ISTORB #IBLOCK%NTW-2< INTG 47 C PRESERVE LAST VALUES OF IBLOCK IN ISTORE INTG 48 303 READ%IG<%IBLOCK%NTW&II-3<,II#1,4002< INTGA 3 IF%EOF%IG<<304,305 INTGA 4 304 REWIND IG INTGA 5 NMORE#0 INTGA 6 GO TO 301 INTGA 7 305 IF%ISEAR .NE. IBLOCK%NTW-2<