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subroutine csrot (n,cx,incx,cy,incy,c,s)
c
c applies a plane rotation, where the cos and sin (c and s) are real
c and the vectors cx and cy are complex.
c jack dongarra, linpack, 3/11/78.
c
complex cx(1),cy(1),ctemp
real c,s
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 = c*cx(ix) + s*cy(iy)
cy(iy) = c*cy(iy) - s*cx(ix)
cx(ix) = ctemp
ix = ix + incx
iy = iy + incy
10 continue
return
c
c code for both increments equal to 1
c
20 do 30 i = 1,n
ctemp = c*cx(i) + s*cy(i)
cy(i) = c*cy(i) - s*cx(i)
cx(i) = ctemp
30 continue
return
end
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