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Annotation of researchv10no/cmd/view2d/num/sdot.f, revision 1.1.1.1

1.1       root        1:       real function sdot(n,sx,incx,sy,incy)
                      2: c
                      3: c     forms the dot product of two vectors.
                      4: c     uses unrolled loops for increments equal to one.
                      5: c     jack dongarra, linpack, 3/11/78.
                      6: c
                      7:       real sx(1),sy(1),stemp
                      8:       integer i,incx,incy,ix,iy,m,mp1,n
                      9: c
                     10:       stemp = 0.0e0
                     11:       sdot = 0.0e0
                     12:       if(n.le.0)return
                     13:       if(incx.eq.1.and.incy.eq.1)go to 20
                     14: c
                     15: c        code for unequal increments or equal increments
                     16: c          not equal to 1
                     17: c
                     18:       ix = 1
                     19:       iy = 1
                     20:       if(incx.lt.0)ix = (-n+1)*incx + 1
                     21:       if(incy.lt.0)iy = (-n+1)*incy + 1
                     22:       do 10 i = 1,n
                     23:         stemp = stemp + sx(ix)*sy(iy)
                     24:         ix = ix + incx
                     25:         iy = iy + incy
                     26:    10 continue
                     27:       sdot = stemp
                     28:       return
                     29: c
                     30: c        code for both increments equal to 1
                     31: c
                     32: c
                     33: c        clean-up loop
                     34: c
                     35:    20 m = mod(n,5)
                     36:       if( m .eq. 0 ) go to 40
                     37:       do 30 i = 1,m
                     38:         stemp = stemp + sx(i)*sy(i)
                     39:    30 continue
                     40:       if( n .lt. 5 ) go to 60
                     41:    40 mp1 = m + 1
                     42:       do 50 i = mp1,n,5
                     43:         stemp = stemp + sx(i)*sy(i) + sx(i + 1)*sy(i + 1) +
                     44:      *   sx(i + 2)*sy(i + 2) + sx(i + 3)*sy(i + 3) + sx(i + 4)*sy(i + 4)
                     45:    50 continue
                     46:    60 sdot = stemp
                     47:       return
                     48:       end

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