[Pw_forum] query on e-ph matrix element

[Axel Kohlmeyer]

On Mon, Dec 12, 2011 at 6:44 PM, Ajit Vallabhaneni <avallabh at purdue.edu> wrote:
> Dear Paolo
>
>      Can you please explain what the variable "zdotc" in elphon.f90 exactly does? I think it calculates the derivative of the potential.  It is declared as an external variable but i couldnot figure out the location it has been calculated. Can you show me the the path as well where it is calculated ?

zdotc is not a variable but a BLAS function:

NAME
       ZDOTC - forms the dot product of a vector

SYNOPSIS
       DOUBLE COMPLEX FUNCTION ZDOTC(N,ZX,INCX,ZY,INCY)

           INTEGER    INCX,INCY,N

           DOUBLE     COMPLEX ZX(*),ZY(*)

PURPOSE
       ZDOTC forms the dot product of a vector.


please note the difference in the meaning of "external"
between C and Fortran. ;)

cheers,
     axel.

>
> Thanks
> Ajit
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-- 
Dr. Axel Kohlmeyer
akohlmey at gmail.com  http://goo.gl/1wk0

College of Science and Technology
Temple University, Philadelphia PA, USA.