# Contents of /trunk/blas/daxpy.f

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```Setting up web subdirectory in repository
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 1 C daxpy.f 2 C is freely available from netlib. It is not subject to any GNU License 3 C set by the authors of the ASCEND math programming system. 4 C \$Date: 1996/04/30 18:14:07 \$ \$Revision: 1.1.1.1 \$ 5 C 6 subroutine daxpy(n,da,dx,incx,dy,incy) 7 c 8 c constant times a vector plus a vector. 9 c uses unrolled loops for increments equal to one. 10 c jack dongarra, linpack, 3/11/78. 11 c 12 double precision dx(*),dy(*),da 13 integer i,incx,incy,ix,iy,m,mp1,n 14 c 15 if(n.le.0)return 16 if (da .eq. 0.0d0) return 17 if(incx.eq.1.and.incy.eq.1)go to 20 18 c 19 c code for unequal increments or equal increments 20 c not equal to 1 21 c 22 ix = 1 23 iy = 1 24 if(incx.lt.0)ix = (-n+1)*incx + 1 25 if(incy.lt.0)iy = (-n+1)*incy + 1 26 do 10 i = 1,n 27 dy(iy) = dy(iy) + da*dx(ix) 28 ix = ix + incx 29 iy = iy + incy 30 10 continue 31 return 32 c 33 c code for both increments equal to 1 34 c 35 c 36 c clean-up loop 37 c 38 20 m = mod(n,4) 39 if( m .eq. 0 ) go to 40 40 do 30 i = 1,m 41 dy(i) = dy(i) + da*dx(i) 42 30 continue 43 if( n .lt. 4 ) return 44 40 mp1 = m + 1 45 do 50 i = mp1,n,4 46 dy(i) = dy(i) + da*dx(i) 47 dy(i + 1) = dy(i + 1) + da*dx(i + 1) 48 dy(i + 2) = dy(i + 2) + da*dx(i + 2) 49 dy(i + 3) = dy(i + 3) + da*dx(i + 3) 50 50 continue 51 return 52 end 53

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