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desruisseaux pushed a commit to branch geoapi-4.0
in repository https://gitbox.apache.org/repos/asf/sis.git
The following commit(s) were added to refs/heads/geoapi-4.0 by this push:
new 7574429b2d Fix documentation that became innacurate after the
improvement done in previous commit.
7574429b2d is described below
commit 7574429b2db1a3d7c7293b1db116e2c5091ebf21
Author: Martin Desruisseaux <[email protected]>
AuthorDate: Sat Apr 27 11:23:27 2024 +0200
Fix documentation that became innacurate after the improvement done in
previous commit.
---
.../apache/sis/referencing/ClenshawSummation.java | 24 +++++++++++++++-------
1 file changed, 17 insertions(+), 7 deletions(-)
diff --git
a/endorsed/src/org.apache.sis.referencing/test/org/apache/sis/referencing/ClenshawSummation.java
b/endorsed/src/org.apache.sis.referencing/test/org/apache/sis/referencing/ClenshawSummation.java
index 96053fb6fa..2831ca0cd3 100644
---
a/endorsed/src/org.apache.sis.referencing/test/org/apache/sis/referencing/ClenshawSummation.java
+++
b/endorsed/src/org.apache.sis.referencing/test/org/apache/sis/referencing/ClenshawSummation.java
@@ -56,10 +56,16 @@ import org.apache.sis.pending.jdk.JDK21;
* This class is used for more complex formulas where the use of spreadsheet
become too difficult.
*
* <h2>Limitations</h2>
- * Current implementation can handle a maximum of 6 terms in the trigonometric
series (see {@link #compute()}).
- * This limit is too short for {@link
org.apache.sis.referencing.operation.projection.EquidistantCylindrical}.
- * It would be possible to generalize using an iterative algorithm. Given that
{@code EquidistantCylindrical}
- * is used less often than Mercator or Lambert projections, we have not done
this optimization yet.
+ * Current implementation can handle a maximum of 8 terms in the trigonometric
series.
+ * This limit is hard-coded in the {@link #compute()} method, but can be
expanded by using
+ * the {@link Precomputation} inner class for generating the {@code compute()}
code.
+ *
+ * <h4>Possible future evolution</h4>
+ * Maybe we should generate series expansions automatically for a given
precision and eccentricity,
+ * adding more terms until the last added term adds a correction smaller than
the desired precision.
+ * Then we could use {@link Precomputation} for generating the corresponding
Clenshaw summation.
+ * This improvement would be needed for planetary CRS, where map projections
may be applied on planet
+ * with higher eccentricity than Earth.
*
* @author Martin Desruisseaux (Geomatys)
*
@@ -346,9 +352,13 @@ public final class ClenshawSummation {
}
/**
- * Performs the Clenshaw summation. Current implementation uses hard-coded
coefficients for 6 terms.
- * See Charles F. F. Karney, Geodesics on an ellipsoid of revolution
(2011) equation 59
- * if generalization to an arbitrary number of coefficients is desired.
+ * Performs the Clenshaw summation. Current implementation uses hard-coded
coefficients for 8 terms.
+ * If more terms are needed, use {@link Precomputation} for generating the
code of this method.
+ *
+ * <h4>Possible future evolution</h4>
+ * It would be possible to compute those terms dynamically using {@link
Precomputation}.
+ * It would be useful if a future Apache SIS version generates series
expansion on-the-fly
+ * for a specified precision and eccentricity.
*
* @see <a href="https://issues.apache.org/jira/browse/SIS-465";>SIS-465</a>
*/
