Added gen command and modified installation instructions for tables

1 files changed, 23 insertions, 6 deletions

diff --git a/INSTALL b/INSTALL
index 0717a0a..f8bef02 100644
--- a/INSTALL
+++ b/INSTALL
@@ -11,7 +11,7 @@ pruning table. If so, about 200Mb should be enough.
 ## On Windows
 
 Try downloading and executing in a terminal the file nissy.exe, then
-follow the instructions in the UNIX section below for downloading and
+follow the instructions in the Tables section below for
 installing the pruning tables.
 If nissy.exe does not work, you can try following the UNIX instructions
 in WSL (Windows Subsystem for Linux) or in a similar environment.
@@ -22,11 +22,28 @@ Sorry for the inconvenience, I don't have a Windows machine to test this on.
 
 Edit the Makefile to match your local configuration (usually not necessary, but you
 may want to change the PREFIX variable) and run make, followed by make install.
-After that, you need to download some files and manually save them to your NISSYDATA
-folder (se manual page, ENVIRONMENT section). If you don't do it nissy can compute
-these files when needed and save them in the correct folders, but some of them
-take hours to generate even for a powerful computer (for reference, the huge pruning
-table takes about 20 hours on my laptop).
+Follows the instructions below to install the pruning tables.
+
+## Tables
+Nissy needs to generate certain large tables to work. These tables are by default
+generated the first time they are needed (e.g the first time you ask to solve a
+certain step) and then saved to a file. The following times nissy simply loads the
+corresponding file from the hard disk.
+
+The very large table for optimal solving can take some time to generate (about 20
+minutes on my fairly old but decent laptop, using 8 CPU threads). All other
+tables are much faster.
+
+You can ask nissy to generate all the tables it will ever need with the gen
+command. It is recommended to use more than one thread, if your CPU has them.
+For example, you can run:
+
+nissy gen -t 8
+
+to generate all tables using 8 threads.
+
+Alternatively, you can simply download all the tables and copy them into the
+correct folder (see manual page, ENVIRONMENT section).
 Choose one of the following:
         https://math.uni.lu/tronto/nissy/nissy-tables-full.zip
         https://math.uni.lu/tronto/nissy/nissy-tables-full.tar.gz