2007-01-11 21:25:52 +00:00
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subroutine slope(y,npts,xpk)
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C Remove best-fit slope from data in y(i). When fitting the straight line,
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C ignore the peak around xpk +/- 2.
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real y(npts)
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real x(100)
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do i=1,npts
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x(i)=i
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enddo
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sumw=0.
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sumx=0.
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sumy=0.
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sumx2=0.
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sumxy=0.
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sumy2=0.
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do i=1,npts
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if(abs(i-xpk).gt.2.0) then
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sumw=sumw + 1.0
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sumx=sumx + x(i)
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sumy=sumy + y(i)
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sumx2=sumx2 + x(i)**2
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sumxy=sumxy + x(i)*y(i)
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sumy2=sumy2 + y(i)**2
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endif
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enddo
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delta=sumw*sumx2 - sumx**2
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a=(sumx2*sumy - sumx*sumxy) / delta
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b=(sumw*sumxy - sumx*sumy) / delta
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do i=1,npts
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y(i)=y(i)-(a + b*x(i))
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enddo
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return
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end
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