subroutine cswapf (n,cx,incx,cy,incy)
c
c interchanges two vectors.
c jack dongarra, linpack, 3/11/78.
c modified 12/3/93, array(1) declarations changed to array(*)
c
complex cx(*),cy(*),ctemp
integer i,incx,incy,ix,iy,n
c
if(n.le.0)return
if(incx.eq.1.and.incy.eq.1)go to 20
c
c code for unequal increments or equal increments not equal
c to 1
c
ix = 1
iy = 1
if(incx.lt.0)ix = (-n+1)*incx + 1
if(incy.lt.0)iy = (-n+1)*incy + 1
do 10 i = 1,n
ctemp = cx(ix)
cx(ix) = cy(iy)
cy(iy) = ctemp
ix = ix + incx
iy = iy + incy
10 continue
return
c
c code for both increments equal to 1
20 do 30 i = 1,n
ctemp = cx(i)
cx(i) = cy(i)
cy(i) = ctemp
30 continue
return
end