1 files changed, 56 insertions, 0 deletions
diff --git a/2.3-1/src/fortran/blas/dswap.f b/2.3-1/src/fortran/blas/dswap.f
new file mode 100644
index 00000000..7f7d1fbb
--- /dev/null
+++ b/2.3-1/src/fortran/blas/dswap.f
@@ -0,0 +1,56 @@
+      subroutine  dswap (n,dx,incx,dy,incy)
+c
+c     interchanges two vectors.
+c     uses unrolled loops for increments equal one.
+c     jack dongarra, linpack, 3/11/78.
+c     modified 12/3/93, array(1) declarations changed to array(*)
+c
+      double precision dx(*),dy(*),dtemp
+      integer i,incx,incy,ix,iy,m,mp1,n
+c
+      if(n.le.0)return
+      if(incx.eq.1.and.incy.eq.1)go to 20
+c
+c       code for unequal increments or equal increments not equal
+c         to 1
+c
+      ix = 1
+      iy = 1
+      if(incx.lt.0)ix = (-n+1)*incx + 1
+      if(incy.lt.0)iy = (-n+1)*incy + 1
+      do 10 i = 1,n
+        dtemp = dx(ix)
+        dx(ix) = dy(iy)
+        dy(iy) = dtemp
+        ix = ix + incx
+        iy = iy + incy
+   10 continue
+      return
+c
+c       code for both increments equal to 1
+c
+c
+c       clean-up loop
+c
+   20 m = mod(n,3)
+      if( m .eq. 0 ) go to 40
+      do 30 i = 1,m
+        dtemp = dx(i)
+        dx(i) = dy(i)
+        dy(i) = dtemp
+   30 continue
+      if( n .lt. 3 ) return
+   40 mp1 = m + 1
+      do 50 i = mp1,n,3
+        dtemp = dx(i)
+        dx(i) = dy(i)
+        dy(i) = dtemp
+        dtemp = dx(i + 1)
+        dx(i + 1) = dy(i + 1)
+        dy(i + 1) = dtemp
+        dtemp = dx(i + 2)
+        dx(i + 2) = dy(i + 2)
+        dy(i + 2) = dtemp
+   50 continue
+      return
+      end