1 double precision function dsum(n,sx,incx) 2* 3* $Id$ 4* 5c 6c takes the sum of the array elements. 7c uses unrolled loops for increment equal to one. 8c jack dongarra, linpack, 3/11/78. 9c modified 3/93 to return if incx .le. 0. 10c 11 double precision sx(*),stemp 12 integer i,incx,m,mp1,n,nincx 13c 14 dsum = 0.0d0 15 stemp = 0.0d0 16 if( n.le.0 .or. incx.le.0 )return 17 if(incx.eq.1)go to 20 18c 19c code for increment not equal to 1 20c 21 nincx = n*incx 22 do 10 i = 1,nincx,incx 23 stemp = stemp + sx(i) 24 10 continue 25 dsum = stemp 26 return 27c 28c code for increment equal to 1 29c 30c 31c clean-up loop 32c 33 20 m = mod(n,6) 34 if( m .eq. 0 ) go to 40 35 do 30 i = 1,m 36 stemp = stemp + sx(i) 37 30 continue 38 if( n .lt. 6 ) go to 60 39 40 mp1 = m + 1 40 do 50 i = mp1,n,6 41 stemp = stemp + sx(i) + sx(i + 1) + sx(i + 2) 42 * + sx(i + 3) + sx(i + 4) + sx(i + 5) 43 50 continue 44 60 dsum = stemp 45 return 46 end 47