Improve docs describing how to install YAC

doc/sphinx/global.txt

@@ -137,6 +137,9 @@
 
 .. _YAXT: https://dkrz-sw.gitlab-pages.dkrz.de/yaxt/
 .. _YAC: https://dkrz-sw.gitlab-pages.dkrz.de/yac/
+.. _libyaml: https://pyyaml.org/wiki/LibYAML
+.. _Autoconf: https://www.gnu.org/software/autoconf/
+.. _Automake: https://www.gnu.org/software/automake/
 
 .. CF conventions
 

doc/sphinx/installation/code/yac.sh

@@ -4,13 +4,29 @@ set -u
 set -e
 set -x
 
+rm -rf yaxt
 rm -rf yac
 
 # manual-begin
-version=3.3.0
 prefix=$HOME/local/yac
 
-git clone -b release-${version} \
+yaxt_version=0.11.2
+git clone -b release-${yaxt_version} \
+    https://gitlab.dkrz.de/dkrz-sw/yaxt.git
+
+cd yaxt
+
+autoreconf -i
+
+./configure --prefix=${prefix} \
+            --with-pic
+
+make all && make install
+
+cd -
+
+yac_version=3.3.0
+git clone -b release-${yac_version} \
     https://gitlab.dkrz.de/dkrz-sw/yac.git
 
 cd yac

doc/sphinx/installation/interpolation.rst

@@ -10,19 +10,12 @@ Enabling flexible interpolation using YAC and PROJ
 PISM's projection-aware interpolation code uses PROJ_\ [#f1]_ to compute *longitude, latitude*
 coordinates of cell centers and cell corners and YAC_ for the interpolation itself.
 
-YAC depends on YAXT_. Use the following commands to install it:
-
-.. literalinclude:: code/yaxt.sh
-   :language: bash
-   :caption: Building YAXT
-   :start-after: manual-begin
-   :end-before: manual-end
-
-Once this is done, build and install YAC:
+YAC depends on YAXT_. Please make sure you have Autoconf_, Automake_, and libyaml_
+installed, then use the following commands to install both YAXT and YAC:
 
 .. literalinclude:: code/yac.sh
    :language: bash
-   :caption: Building YAC
+   :caption: Building YAXT and YAC
    :start-after: manual-begin
    :end-before: manual-end