Original Version

1 files changed, 27 insertions, 0 deletions

diff --git a/2.3-1/src/fortran/blas/drotg.f b/2.3-1/src/fortran/blas/drotg.f
new file mode 100644
index 00000000..67838e2c
--- /dev/null
+++ b/2.3-1/src/fortran/blas/drotg.f
@@ -0,0 +1,27 @@
+      subroutine drotg(da,db,c,s)
+c
+c     construct givens plane rotation.
+c     jack dongarra, linpack, 3/11/78.
+c
+      double precision da,db,c,s,roe,scale,r,z
+c
+      roe = db
+      if( dabs(da) .gt. dabs(db) ) roe = da
+      scale = dabs(da) + dabs(db)
+      if( scale .ne. 0.0d0 ) go to 10
+         c = 1.0d0
+         s = 0.0d0
+         r = 0.0d0
+         z = 0.0d0
+         go to 20
+   10 r = scale*dsqrt((da/scale)**2 + (db/scale)**2)
+      r = dsign(1.0d0,roe)*r
+      c = da/r
+      s = db/r
+      z = 1.0d0
+      if( dabs(da) .gt. dabs(db) ) z = s
+      if( dabs(db) .ge. dabs(da) .and. c .ne. 0.0d0 ) z = 1.0d0/c
+   20 da = r
+      db = z
+      return
+      end