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aw0a |
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C dasum.f |
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C is freely available from netlib. It is not subject to any GNU License |
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C set by the authors of the ASCEND math programming system. |
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C $Date: 1996/04/30 18:14:07 $ $Revision: 1.1.1.1 $ |
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C |
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double precision function dasum(n,dx,incx) |
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c |
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c takes the sum of the absolute values. |
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c jack dongarra, linpack, 3/11/78. |
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c |
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double precision dx(*),dtemp |
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integer i,incx,m,mp1,n,nincx |
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c |
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dasum = 0.0d0 |
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dtemp = 0.0d0 |
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if(n.le.0)return |
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if(incx.eq.1)go to 20 |
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c |
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c code for increment not equal to 1 |
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c |
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nincx = n*incx |
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do 10 i = 1,nincx,incx |
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dtemp = dtemp + dabs(dx(i)) |
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10 continue |
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dasum = dtemp |
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return |
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c |
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c code for increment equal to 1 |
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c |
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c |
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c clean-up loop |
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c |
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20 m = mod(n,6) |
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if( m .eq. 0 ) go to 40 |
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do 30 i = 1,m |
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dtemp = dtemp + dabs(dx(i)) |
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30 continue |
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if( n .lt. 6 ) go to 60 |
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40 mp1 = m + 1 |
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do 50 i = mp1,n,6 |
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dtemp = dtemp + dabs(dx(i)) + dabs(dx(i + 1)) + dabs(dx(i + 2)) |
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* + dabs(dx(i + 3)) + dabs(dx(i + 4)) + dabs(dx(i + 5)) |
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50 continue |
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60 dasum = dtemp |
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return |
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end |
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