made a copy

git-svn-id: https://openmodelica.org/svn/OpenModelica/trunk@1697 f25d12d1-65f4-0310-ae8a-bbce733d8d8e

c_runtime/r1mpyq.f

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+      subroutine r1mpyq(m,n,a,lda,v,w)
+      integer m,n,lda
+      double precision a(lda,n),v(n),w(n)
+c     **********
+c
+c     subroutine r1mpyq
+c
+c     given an m by n matrix a, this subroutine computes a*q where
+c     q is the product of 2*(n - 1) transformations
+c
+c           gv(n-1)*...*gv(1)*gw(1)*...*gw(n-1)
+c
+c     and gv(i), gw(i) are givens rotations in the (i,n) plane which
+c     eliminate elements in the i-th and n-th planes, respectively.
+c     q itself is not given, rather the information to recover the
+c     gv, gw rotations is supplied.
+c
+c     the subroutine statement is
+c
+c       subroutine r1mpyq(m,n,a,lda,v,w)
+c
+c     where
+c
+c       m is a positive integer input variable set to the number
+c         of rows of a.
+c
+c       n is a positive integer input variable set to the number
+c         of columns of a.
+c
+c       a is an m by n array. on input a must contain the matrix
+c         to be postmultiplied by the orthogonal matrix q
+c         described above. on output a*q has replaced a.
+c
+c       lda is a positive integer input variable not less than m
+c         which specifies the leading dimension of the array a.
+c
+c       v is an input array of length n. v(i) must contain the
+c         information necessary to recover the givens rotation gv(i)
+c         described above.
+c
+c       w is an input array of length n. w(i) must contain the
+c         information necessary to recover the givens rotation gw(i)
+c         described above.
+c
+c     subroutines called
+c
+c       fortran-supplied ... dabs,dsqrt
+c
+c     argonne national laboratory. minpack project. march 1980.
+c     burton s. garbow, kenneth e. hillstrom, jorge j. more
+c
+c     **********
+      integer i,j,nmj,nm1
+      double precision cos,one,sin,temp
+      data one /1.0d0/
+c
+c     apply the first set of givens rotations to a.
+c
+      nm1 = n - 1
+      if (nm1 .lt. 1) go to 50
+      do 20 nmj = 1, nm1
+         j = n - nmj
+         if (dabs(v(j)) .gt. one) cos = one/v(j)
+         if (dabs(v(j)) .gt. one) sin = dsqrt(one-cos**2)
+         if (dabs(v(j)) .le. one) sin = v(j)
+         if (dabs(v(j)) .le. one) cos = dsqrt(one-sin**2)
+         do 10 i = 1, m
+            temp = cos*a(i,j) - sin*a(i,n)
+            a(i,n) = sin*a(i,j) + cos*a(i,n)
+            a(i,j) = temp
+   10       continue
+   20    continue
+c
+c     apply the second set of givens rotations to a.
+c
+      do 40 j = 1, nm1
+         if (dabs(w(j)) .gt. one) cos = one/w(j)
+         if (dabs(w(j)) .gt. one) sin = dsqrt(one-cos**2)
+         if (dabs(w(j)) .le. one) sin = w(j)
+         if (dabs(w(j)) .le. one) cos = dsqrt(one-sin**2)
+         do 30 i = 1, m
+            temp = cos*a(i,j) + sin*a(i,n)
+            a(i,n) = -sin*a(i,j) + cos*a(i,n)
+            a(i,j) = temp
+   30       continue
+   40    continue
+   50 continue
+      return
+c
+c     last card of subroutine r1mpyq.
+c
+      end