SYNOPSIS

subroutine zscal(n,za,zx,incx)

    

c scales a vector by a constant.

    

c jack dongarra, 3/11/78.

    

c modified to correct problem with negative increment, 8/21/90.

    

double complex za,zx(1)

    

integer i,incx,ix,n

    

if(n.le.0)return

    

if(incx.eq.1)go to 20

    

c code for increment not equal to 1

    

ix = 1

    

if(incx.lt.0)ix = (-n+1)*incx + 1

    

do 10 i = 1,n

    

zx(ix) = za*zx(ix)

    

ix = ix + incx

    

10 continue

    

return

    

c code for increment equal to 1

    

20 do 30 i = 1,n

    

zx(i) = za*zx(i)

    

30 continue

    

return

    

end

PURPOSE