[sis] 01/06: Minor clarification in the comment about NaN values in map projection results.

[desruisseaux]

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desruisseaux pushed a commit to branch geoapi-4.0
in repository https://gitbox.apache.org/repos/asf/sis.git

commit 84be76a9f86904aa3be7bcc8b3848cedf0a6486c
Author: Martin Desruisseaux <martin.desruisse...@geomatys.com>
AuthorDate: Wed Nov 10 11:09:47 2021 +0100

    Minor clarification in the comment about NaN values in map projection 
results.
---
 .../referencing/operation/projection/TransverseMercator.java   | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git 
a/core/sis-referencing/src/main/java/org/apache/sis/referencing/operation/projection/TransverseMercator.java
 
b/core/sis-referencing/src/main/java/org/apache/sis/referencing/operation/projection/TransverseMercator.java
index 01dd54d..67e7799 100644
--- 
a/core/sis-referencing/src/main/java/org/apache/sis/referencing/operation/projection/TransverseMercator.java
+++ 
b/core/sis-referencing/src/main/java/org/apache/sis/referencing/operation/projection/TransverseMercator.java
@@ -419,11 +419,11 @@ public class TransverseMercator extends 
NormalizedProjection {
              * In Mercator projection, y values tend toward infinity for 
latitudes close to ±90°.
              * In Transverse Mercator, x values tend toward infinity for 
longitudes close to ±90°
              * at equator and after subtraction of central meridian. After we 
pass the 90° limit,
-             * the Transverse Mercator results at (90° + Δ) are the same as 
for (90° - Δ).
+             * the Transverse Mercator formulas produce the same values at 
(90° + Δ) than at (90° - Δ).
              *
              * Problem is that 90° is an ordinary longitude value, not even 
close to the limit of longitude
              * values range (±180°). So having f(π/2+Δ, φ) = f(π/2-Δ, φ) 
results in wrong behavior in some
-             * algorithms like the one used by 
Envelopes.transform(CoordinateOperation, Envelope).
+             * algorithms like the one used by 
`Envelopes.transform(CoordinateOperation, Envelope)`.
              * Since a distance of 90° from central meridian is far outside 
the Transverse Mercator
              * domain of validity anyway, we do not let the user go further.
              *
@@ -437,12 +437,12 @@ public class TransverseMercator extends 
NormalizedProjection {
              *
              * Reminder: difference between returning NaN or throwing an 
exception is as below:
              *
-             *    - NaN means "value does not exist".
-             *    - ProjectionException means "values exist but can not be 
computed".
+             *    - NaN means "value does not exist or is not a real number".
+             *    - ProjectionException means "value should exist but can not 
be computed".
              *
              * So it is okay to return NaN for values located at Δλ > 90°, but 
we should throw an exception
              * for values at Δλ ≤ 90° if we can not compute them. Previous 
version of this method was throwing
-             * an exception. Now that we accept all longitudes up to 90°, we 
return NaN instead.
+             * an exception for all Δλ > 70°. Now that we accept all 
longitudes up to 90°, we return NaN instead.
              */
             if (Math.abs(IEEEremainder(λ, 2*PI)) > 90 * (PI/180)) {         // 
More costly check.
                 return outsideDomainOfValidity(dstPts, dstOff, derivate);