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-rw-r--r--docs/source/operations/projections/merc.rst13
-rw-r--r--docs/source/operations/projections/tmerc.rst2
2 files changed, 9 insertions, 6 deletions
diff --git a/docs/source/operations/projections/merc.rst b/docs/source/operations/projections/merc.rst
index 62aa5bc9..c474009f 100644
--- a/docs/source/operations/projections/merc.rst
+++ b/docs/source/operations/projections/merc.rst
@@ -6,9 +6,10 @@ Mercator
The Mercator projection is a cylindrical map projection that origins from the 15th
century. It is widely recognized as the first regularly used map projection.
-The projection has the property that a rhumb line, a course of constant
-heading, projects to a straight line. This makes it suitable for
-navigational purposes.
+It is a conformal projection in which the equator projects to a straight
+line at constant scale. The projection has the property that a rhumb
+line, a course of constant heading, projects to a straight line. This
+makes it suitable for navigational purposes.
+---------------------+----------------------------------------------------------+
@@ -99,7 +100,7 @@ Forward projection
.. math::
- \psi &= \log \tan \biggl(\frac{\pi}{4} + \frac{\phi}{2} \biggr)\\
+ \psi &= \ln \tan \biggl(\frac{\pi}{4} + \frac{\phi}{2} \biggr)\\
&= \sinh^{-1}\tan\phi
The quantity :math:`\psi` is the isometric latitude.
@@ -143,9 +144,9 @@ Forward projection
.. math::
- \psi &= \log\tan\biggl(\frac\pi4 + \frac{\phi}2\biggr)
+ \psi &= \ln\tan\biggl(\frac\pi4 + \frac{\phi}2\biggr)
-\frac12 e
- \log \biggl(\frac{1 + e \sin\phi}{1 - e \sin\phi}\biggr)\\
+ \ln \biggl(\frac{1 + e \sin\phi}{1 - e \sin\phi}\biggr)\\
&= \sinh^{-1}\tan\phi - e \tanh^{-1}(e \sin\phi)
diff --git a/docs/source/operations/projections/tmerc.rst b/docs/source/operations/projections/tmerc.rst
index 3b2a0190..7fed3846 100644
--- a/docs/source/operations/projections/tmerc.rst
+++ b/docs/source/operations/projections/tmerc.rst
@@ -5,6 +5,8 @@ Transverse Mercator
********************************************************************************
The transverse Mercator projection in its various forms is the most widely used projected coordinate system for world topographical and offshore mapping.
+It is a conformal projection in which a chosen meridian projects to a
+straight line at constant scale.
+---------------------+----------------------------------------------------------+
| **Classification** | Transverse and oblique cylindrical |