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subroutine zswap (n,zx,incx,zy,incy)
c
c interchanges two vectors.
c jack dongarra, 3/11/78.
c modified 12/3/93, array(1) declarations changed to array(*)
c
double complex zx(*),zy(*),ztemp
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
ztemp = zx(ix)
zx(ix) = zy(iy)
zy(iy) = ztemp
ix = ix + incx
iy = iy + incy
10 continue
return
c
c code for both increments equal to 1
20 do 30 i = 1,n
ztemp = zx(i)
zx(i) = zy(i)
zy(i) = ztemp
30 continue
return
end
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