summaryrefslogtreecommitdiff
path: root/2.3-1/src/fortran/blas/idamax.f
diff options
context:
space:
mode:
Diffstat (limited to '2.3-1/src/fortran/blas/idamax.f')
-rw-r--r--2.3-1/src/fortran/blas/idamax.f39
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