[petsc-users] Precision Problem in computing Eigenvalue

[Jose E. Roman]

El 05/01/2015, a las 11:28, Ajay Manwani escribió:

> Hello, Thank you very much for your reply.
>  i installed PETSC in quad and complex mode without C++,(./configure --download-mpich --with-fc-gfortran --with-cc=gcc --with-cxx=g++  --with-scalar-type=complex  --with-precision=__float128 --download-f2cblaslapack )
>  
> It worked fine but problem is eigenvalues we get by PEPSolve() are correct and then as i use PEPGetPair(), i get absurd values. 
> I want to write eigenvalues and eigenpairs to a text file hence i need to use PEPGetEigenpair command
> 
> 
> --Ajay

In quad precision you need to explicitly cast to double in printf statements, see e.g.
http://www.grycap.upv.es/slepc/documentation/current/src/eps/examples/tutorials/ex1.c.html

Is this your problem? Otherwise, send the code excerpt where you extract and print eigenpairs.

Jose