61 lines
1.4 KiB
Fortran
61 lines
1.4 KiB
Fortran
SUBROUTINE fit(x,y,ndata,sig,mwt,a,b,siga,sigb,chi2,q)
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INTEGER mwt,ndata
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REAL a,b,chi2,q,siga,sigb,sig(ndata),x(ndata),y(ndata)
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CU USES gammq
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INTEGER i
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REAL sigdat,ss,st2,sx,sxoss,sy,t,wt,gammq
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sx=0.
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sy=0.
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st2=0.
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b=0.
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if(mwt.ne.0) then
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ss=0.
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do 11 i=1,ndata
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wt=1./(sig(i)**2)
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ss=ss+wt
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sx=sx+x(i)*wt
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sy=sy+y(i)*wt
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11 continue
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else
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do 12 i=1,ndata
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sx=sx+x(i)
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sy=sy+y(i)
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12 continue
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ss=float(ndata)
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endif
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sxoss=sx/ss
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if(mwt.ne.0) then
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do 13 i=1,ndata
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t=(x(i)-sxoss)/sig(i)
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st2=st2+t*t
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b=b+t*y(i)/sig(i)
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13 continue
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else
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do 14 i=1,ndata
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t=x(i)-sxoss
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st2=st2+t*t
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b=b+t*y(i)
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14 continue
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endif
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b=b/st2
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a=(sy-sx*b)/ss
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siga=sqrt((1.+sx*sx/(ss*st2))/ss)
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sigb=sqrt(1./st2)
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chi2=0.
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if(mwt.eq.0) then
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do 15 i=1,ndata
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chi2=chi2+(y(i)-a-b*x(i))**2
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15 continue
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q=1.
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sigdat=sqrt(chi2/(ndata-2))
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siga=siga*sigdat
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sigb=sigb*sigdat
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else
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do 16 i=1,ndata
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chi2=chi2+((y(i)-a-b*x(i))/sig(i))**2
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16 continue
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q=gammq(0.5*(ndata-2),0.5*chi2)
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endif
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return
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END
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