[gegl] gegl-matrix: improve description of gegl_matrix3_originate()

[N/A <ell src gnome org>]

commit 2f1ba90c6525ef3e3f927a7ce3df7c684d7569e3
Author: Ell <ell_se yahoo com>
Date:   Tue Nov 21 11:53:52 2017 -0500

    gegl-matrix: improve description of gegl_matrix3_originate()

 gegl/gegl-matrix.c |   13 ++++++-------
 gegl/gegl-matrix.h |   13 ++++++++++---
 2 files changed, 16 insertions(+), 10 deletions(-)
---
diff --git a/gegl/gegl-matrix.c b/gegl/gegl-matrix.c
index 4d57e38..119f230 100644
--- a/gegl/gegl-matrix.c
+++ b/gegl/gegl-matrix.c
@@ -197,17 +197,16 @@ gegl_matrix3_multiply (GeglMatrix3 *left,
 
 void
 gegl_matrix3_originate (GeglMatrix3 *matrix,
-                   gdouble x,
-                   gdouble y)
+                        gdouble      x,
+                        gdouble      y)
 {
-
   /* assumes last row is [0 0 1] (true for affine transforms) */
   matrix->coeff [0][2] = matrix->coeff [0][0] * (-x) +
-                  matrix->coeff [0][1] * (-y) +
-                  matrix->coeff [0][2] + x;
+                         matrix->coeff [0][1] * (-y) +
+                         matrix->coeff [0][2] + x;
   matrix->coeff [1][2] = matrix->coeff [1][0] * (-x) +
-                  matrix->coeff [1][1] * (-y) +
-                  matrix->coeff [1][2] + y;
+                         matrix->coeff [1][1] * (-y) +
+                         matrix->coeff [1][2] + y;
 }
 
 void
diff --git a/gegl/gegl-matrix.h b/gegl/gegl-matrix.h
index 76a1ee9..8b68612 100644
--- a/gegl/gegl-matrix.h
+++ b/gegl/gegl-matrix.h
@@ -146,12 +146,19 @@ void       gegl_matrix3_multiply        (GeglMatrix3 *left,
  * @x: x coordinate of new origin
  * @y: y coordinate of new origin.
  *
- * Hmm not quite sure what this does.
+ * Shift the origin of the transformation specified by @matrix
+ * to (@x, @y). In other words, calculate the matrix that:
+ *
+ * 1. Translates the input by (-@x, -@y).
+ *
+ * 2. Transforms the result using the original @matrix.
+ *
+ * 3. Translates the result by (@x, @y).
  *
  */
 void       gegl_matrix3_originate       (GeglMatrix3 *matrix,
-                                         gdouble     x,
-                                         gdouble     y);
+                                         gdouble      x,
+                                         gdouble      y);
 
 
 /**