Merge branch 'hack_doconcurrent' of github.com:xcompact3d/x3div into hack_doconcurrent

Author: rfj82982

src/parameters.f90

@@ -116,7 +116,11 @@ subroutine parameter()
   dy2 = dy * dy
   dz2 = dz * dz
 
-  xnu=one/re
+  if (abs(re) > epsilon(re)) then
+     xnu = one / re
+  else
+     xnu = zero
+  endif
 
   anglex = sin(pi*angle/180._mytype)
   angley = cos(pi*angle/180._mytype)

src/thomas.f90

@@ -202,8 +202,17 @@ subroutine zthomas_12(tt, ff, fs, fw, nx, ny, nz)
 
   end subroutine zthomas_12
 
-  ! Thomas algorithm for a 1D vector
-  subroutine thomas1d(tt, ff, fs, fw, nn)
+  !
+  ! Thomas algorithm for a 1D vector (solve My = x with tri-diagonal M)
+  ! See comments in the subroutine prepare (x3d_operator_1d.f90)
+  !
+  ! tt, inout, vector x and y
+  ! ff, in, upper diagonal of the tri-diagonal matrix
+  ! fs, in, used during the forward step
+  ! fw, in, used during the backward step
+  ! nn, in, size of the vector
+  !
+  pure subroutine thomas1d(tt, ff, fs, fw, nn)
 
     implicit none