avoid Intel/GCC BLAS ABI incompatibility by avoiding blas functions

i.e. incorrect behaviour when ifx combined with (GCC compiled) Openblas

fix replaces zdotc function (return result passing being the problem) with zgemv subroutine

Author: Jerome Jackson

src/wannierise.F90

@@ -1287,7 +1287,6 @@ subroutine precond_search_direction(cdodq, cdodq_r, cdodq_precond, cdodq_precond
       integer, intent(in) :: optimisation
 
       ! local
-      complex(kind=dp), external :: zdotc
       complex(kind=dp) :: fac, rdotk
       real(kind=dp) :: rvec_cart(3)
       real(kind=dp) :: alpha_precond
@@ -1408,8 +1407,8 @@ subroutine internal_search_direction(cdodq_precond_loc, cdqkeep_loc, iter, lprin
       logical, intent(inout) :: lrandom
 
       ! local
-      complex(kind=dp), external :: zdotc
       integer :: m
+      complex(kind=dp) :: zres
 
       m = count(dist_k == mpirank(comm))*num_wann*num_wann ! for dimensioning
 
@@ -1419,9 +1418,13 @@ subroutine internal_search_direction(cdodq_precond_loc, cdqkeep_loc, iter, lprin
 
       ! gcnorm1 = Tr[gradient . gradient] -- NB gradient is anti-Hermitian
       if (wann_control%precond) then
-        gcnorm1 = real(zdotc(m, cdodq_precond_loc, 1, cdodq_loc, 1), dp)
+        ! compute (zdotc) cdodq_precond_loc.cdodq_loc^c
+        call zgemv('c', m, 1, cmplx_1, cdodq_precond_loc, m, cdodq_loc, 1, cmplx_0, zres, 1)
+        gcnorm1 = real(zres, dp)
       else
-        gcnorm1 = real(zdotc(m, cdodq_loc, 1, cdodq_loc, 1), dp)
+        ! compute (zdotc) cdodq_loc.cdodq_loc^c
+        call zgemv('c', m, 1, cmplx_1, cdodq_loc, m, cdodq_loc, 1, cmplx_0, zres, 1)
+        gcnorm1 = real(zres, dp)
       endif
       call comms_allreduce(gcnorm1, 1, 'SUM', error, comm)
       if (allocated(error)) return
@@ -1468,7 +1471,9 @@ subroutine internal_search_direction(cdodq_precond_loc, cdqkeep_loc, iter, lprin
 
       ! calculate gradient along search direction - Tr[gradient . search direction]
       ! NB gradient is anti-hermitian
-      doda0 = -real(zdotc(m, cdodq_loc, 1, cdq_loc, 1), dp)
+      ! compute (zdotc) cdodq_loc.cdq_loc^c
+      call zgemv('c', m, 1, cmplx_1, cdodq_loc, m, cdq_loc, 1, cmplx_0, zres, 1)
+      doda0 = -real(zres, dp)
 
       call comms_allreduce(doda0, 1, 'SUM', error, comm)
       if (allocated(error)) return
@@ -1489,7 +1494,9 @@ subroutine internal_search_direction(cdodq_precond_loc, cdqkeep_loc, iter, lprin
           gcfac = 0.0_dp
 
           ! re-calculate gradient along search direction
-          doda0 = -real(zdotc(m, cdodq_loc, 1, cdq_loc, 1), dp)
+          ! compute (zdotc) cdodq_loc.cdq_loc^c
+          call zgemv('c', m, 1, cmplx_1, cdodq_loc, m, cdq_loc, 1, cmplx_0, zres, 1)
+          doda0 = -real(zres, dp)
 
           call comms_allreduce(doda0, 1, 'SUM', error, comm)
           if (allocated(error)) return