diff options
Diffstat (limited to '2.3-1/src/fortran/blas/idamax.f')
-rw-r--r-- | 2.3-1/src/fortran/blas/idamax.f | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/2.3-1/src/fortran/blas/idamax.f b/2.3-1/src/fortran/blas/idamax.f new file mode 100644 index 00000000..59d80dc4 --- /dev/null +++ b/2.3-1/src/fortran/blas/idamax.f @@ -0,0 +1,39 @@ + integer function idamax(n,dx,incx) +c +c finds the index of element having max. absolute value. +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 dx(*),dmax + integer i,incx,ix,n +c + idamax = 0 + if( n.lt.1 .or. incx.le.0 ) return + idamax = 1 + if(n.eq.1)return + if(incx.eq.1)go to 20 +c +c code for increment not equal to 1 +c + ix = 1 + dmax = dabs(dx(1)) + ix = ix + incx + do 10 i = 2,n + if(dabs(dx(ix)).le.dmax) go to 5 + idamax = i + dmax = dabs(dx(ix)) + 5 ix = ix + incx + 10 continue + return +c +c code for increment equal to 1 +c + 20 dmax = dabs(dx(1)) + do 30 i = 2,n + if(dabs(dx(i)).le.dmax) go to 30 + idamax = i + dmax = dabs(dx(i)) + 30 continue + return + end |