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