From 2731a87ef7ed324fb81a5778f998ef5e31c6388b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Ne=C4=8Dada?= <marek.necada@furuno.fi>
Date: Mon, 6 Jun 2022 13:22:23 +0300
Subject: [PATCH] Installation on Android.

---
 README.md                |   4 ++
 notes/INSTALL_ANDROID.md | 107 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 111 insertions(+)
 create mode 100644 notes/INSTALL_ANDROID.md

diff --git a/README.md b/README.md
index e6c55d0..355cf17 100644
--- a/README.md
+++ b/README.md
@@ -89,6 +89,9 @@ Special care might need to be taken when installing QPMS in cluster environments
 Specific installation instructions for Aalto University's Triton cluster
 can be found in a [separate document][TRITON-README].
 
+Instructions for installation on Android-based devices are
+in [another document][INSTALL-ANDROID].
+
 
 Documentation
 =============
@@ -172,6 +175,7 @@ in Telegram!
 [GSL]: https://www.gnu.org/software/gsl/
 [cmake]: https://cmake.org
 [TRITON-README]: README.Triton.md
+[INSTALL-ANDROID]: notes/INSTALL_ANDROID.md
 [tutorial-finite]: finite_systems.md
 [tutorial-infinite]: lattices.md
 [doxygen]: http://doxygen.nl/
diff --git a/notes/INSTALL_ANDROID.md b/notes/INSTALL_ANDROID.md
new file mode 100644
index 0000000..76a9fd7
--- /dev/null
+++ b/notes/INSTALL_ANDROID.md
@@ -0,0 +1,107 @@
+# Installing QPMS on Android/AOSP (-based) systems
+
+Yes, it is possible. Basically all you need is a device capable of running [Termux](https://termux.com/) with enough memory to build everything.
+
+The following instructions have been tested with Termux version 0.118.0 on
+[e/OS/ R development build on a Samsung Galaxy S10e](https://doc.e.foundation/devices/beyond0lte/install)
+([e-1.0-r-20220526188878-dev-beyond0lte](https://images.ecloud.global/dev/beyond0lte/)).
+Presumably, they should work also on stock Android as well, but who
+in their right mind would run all the spyware by Google & al.?
+
+Physical keyboard or [remote access](https://wiki.termux.com/wiki/Remote_Access) is strongly recommended. :D
+
+## Get Termux
+
+Just [install the Termux app from F-Droid or Github as per instructions](https://github.com/termux/termux-app#f-droid).
+
+Open Termux; the following steps of these instructions are basically
+just commands you need to type in Termux.
+
+## Install prerequisities from termux repositories
+
+```
+pkg install python3 cmake git clang build-essential binutils
+```
+
+## Build and install GSL
+
+```
+curl -O https://www.nic.funet.fi/pub/gnu/ftp.gnu.org/pub/gnu/gsl/gsl-latest.tar.gz
+tar xf gsl-latest.tar.gz
+cd gsl-2.7.1
+./configure --prefix=$PREFIX
+make    # add -j4 or so to make it faster on multicore systems
+make install
+cd -
+```
+
+## Build and install OpenBLAS
+
+```
+git clone https://github.com/xianyi/OpenBLAS.git
+cd OpenBLAS
+make
+make PREFIX=$PREFIX install
+cd -
+```
+
+### Workaround for "broken" setup.py script
+
+The goal is to fix `setup.py` so that it finds the correct libraries automatically, but in the meantime, you can use this workaround to get the Python part of QPMS installed:
+
+```
+ln -s $PREFIX/lib/libopenblas.so $PREFIX/LIB/liblapacke.so
+```
+
+## Build and install Numpy
+
+(Successful build requires the `MATHLIB` environmental variable set, otherwise linking will fail; see https://wiki.termux.com/wiki/Python.)
+
+```
+MATHLIB=m pip3 install numpy
+```
+
+### Install Sympy
+
+```
+pip3 install sympy
+```
+
+## Build and install QPMS
+
+```
+git clone https://repo.or.cz/qpms.git
+cd qpms
+cmake -DCMAKE_INSTALL_PREFIX=$PREFIX . # ugly, TODO make a separate build tree!
+make install
+
+python3 setup.py install
+```
+
+Hopefully, QPMS has installed successfully. At this point, you should be able
+to import and use QPMS with some exceptions. First, there is some legacy code
+in the `qpms.qpms_p` module (which is no longer imported automatically with
+bare `import qpms`). You shouldn't need this unless you are trying to run some
+historic Jupyter notebooks or other old custom scripts. It contains a scipy
+dependence, and scipy is hard to get working in Android environment (as
+it requires a Fortran compiler to build).
+
+## Install matplotlib
+
+If you try to run just `pip3 install matplotlib` in Termux, it might likely
+fail when installing the `pillow` dependency.
+First, according to [Termux wiki](https://wiki.termux.com/wiki/Python#Python_module_installation_tips_and_tricks),
+pillow depends on `libpng` and `libjpeg-turbo`, which are fortunately
+available in Termux packages.
+Second, pillow instalation requires an additional environment variable
+`LDFLAGS="-L/system/lib64"` to be set on 64-bit devices.
+
+Hence:
+```
+pkg install libpng libjpeg-turbo
+export LDFLAGS="-L/system/lib64" # on 64-bit devices
+pip3 install matplotlib
+```
+
+After this step, you should be able to run the command-line scripts
+from `misc/` directory and examples from `examples/` directory.