XSHELLS: ./configure warning: multi-threaded SHTns not found

[Former user]

Hi, When I try to install XSHELLS by running ./configure, the computer will report "warning,multi-threaded SHTns not found".But in fact, I installed SHTns by running "./configure --enable-openmp".

so,what's the problem ?

BY the way,when I ran test example“SHT_example”,it reported well. I use fftw-3.3.8,shtns-2.1.

Thank you if you can share your idea with me!

[bin du]

like this.......

[Nathanaël Schaeffer]

Hi, sorry for the late answer. By the way, you should post this issue on the xshells bugtracker.

First, you can still work with xshells even if the multi-threaded SHTns is not found. Actually, most xshells executables (xsbig, xsbig_hyb, xsbig_mpi) use the single-threaded SHTns. Only for VERY big runs you would need xsbig_hyb2, which needs the multi-threaded SHTns.

Now, if you want to fix this warning:

You should install shtns somewhere, and then tell xshells where to find it. For instance, from the shtns folder:

./configure --enable-openmp --prefix=$HOME/usr
make
make install

repeat with --enable-openmp to also install the single-threaded version:

./configure --prefix=$HOME/usr
make
make install

and then for xshells, in the xshells folder

./configure --prefix=$HOME/usr
make xsbig

Note that for this last xshells configure and make, the --prefix option is used to find libraries rather than to install xshells. This way it should work.

[Nathanaël Schaeffer]

Update: If you really used shtns-2.1 as you mentionned in your opening post it is no wonder: multi-threaded transforms have been introduced in shtns-2.2. Actually for xshells, you should use at least shtns-2.3.1, but the latest version is always adivsed.