diff options
Diffstat (limited to '2.3-1/src/fortran/blas/dscal.f')
-rw-r--r-- | 2.3-1/src/fortran/blas/dscal.f | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/2.3-1/src/fortran/blas/dscal.f b/2.3-1/src/fortran/blas/dscal.f new file mode 100644 index 00000000..e1467faf --- /dev/null +++ b/2.3-1/src/fortran/blas/dscal.f @@ -0,0 +1,43 @@ + subroutine dscal(n,da,dx,incx) +c +c scales a vector by a constant. +c uses unrolled loops for increment equal to one. +c jack dongarra, linpack, 3/11/78. +c modified 3/93 to return if incx .le. 0. +c modified 12/3/93, array(1) declarations changed to array(*) +c + double precision da,dx(*) + integer i,incx,m,mp1,n,nincx +c + if( n.le.0 .or. incx.le.0 )return + if(incx.eq.1)go to 20 +c +c code for increment not equal to 1 +c + nincx = n*incx + do 10 i = 1,nincx,incx + dx(i) = da*dx(i) + 10 continue + return +c +c code for increment equal to 1 +c +c +c clean-up loop +c + 20 m = mod(n,5) + if( m .eq. 0 ) go to 40 + do 30 i = 1,m + dx(i) = da*dx(i) + 30 continue + if( n .lt. 5 ) return + 40 mp1 = m + 1 + do 50 i = mp1,n,5 + dx(i) = da*dx(i) + dx(i + 1) = da*dx(i + 1) + dx(i + 2) = da*dx(i + 2) + dx(i + 3) = da*dx(i + 3) + dx(i + 4) = da*dx(i + 4) + 50 continue + return + end |