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Fix decoding of even lat=0 + odd lat=0 which can have 3 results (-90, 0, +90)

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Oliver Jowett 2015-08-17 18:07:40 +01:00
parent 6d37952b14
commit e438e1e0c5
1 changed files with 20 additions and 2 deletions
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22
cpr.c
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@ -250,8 +250,26 @@ int decodeCPRsurface(double reflat, double reflon,
// reflat=-40, rlat=4, use rlat=4 // reflat=-40, rlat=4, use rlat=4
// reflat=-40, rlat=6, use rlat=6-90 = -84 // reflat=-40, rlat=6, use rlat=6-90 = -84
if ( (rlat0 - reflat) > 45 ) rlat0 -= 90; // As a special case, -90, 0 and +90 all encode to zero, so
if ( (rlat1 - reflat) > 45 ) rlat1 -= 90; // there's a little extra work to do there.
if (rlat0 == 0) {
if (reflat < -45)
rlat0 = -90;
else if (reflat > 45)
rlat0 = 90;
} else if ((rlat0 - reflat) > 45) {
rlat0 -= 90;
}
if (rlat1 == 0) {
if (reflat < -45)
rlat1 = -90;
else if (reflat > 45)
rlat1 = 90;
} else if ((rlat1 - reflat) > 45) {
rlat1 -= 90;
}
// Check to see that the latitude is in range: -90 .. +90 // Check to see that the latitude is in range: -90 .. +90
if (rlat0 < -90 || rlat0 > 90 || rlat1 < -90 || rlat1 > 90) if (rlat0 < -90 || rlat0 > 90 || rlat1 < -90 || rlat1 > 90)