subroutine zdrotf (n,zx,incx,zy,incy,c,s) c c applies a plane rotation, where the cos and sin (c and s) are c double precision and the vectors zx and zy are double complex. c jack dongarra, linpack, 3/11/78. c double complex zx(1),zy(1),ztemp double precision 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 ztemp = c*zx(ix) + s*zy(iy) zy(iy) = c*zy(iy) - s*zx(ix) zx(ix) = ztemp 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 ztemp = c*zx(i) + s*zy(i) zy(i) = c*zy(i) - s*zx(i) zx(i) = ztemp 30 continue return end