computechi2¶
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class
pydl.pydlutils.math.
computechi2
(bvec, sqivar, amatrix)[source]¶ Bases:
object
Solve the linear set of equations A x = b using SVD.
The attributes of this class are all read-only properties, implemented with
lazyproperty
.Parameters: bvec :
numpy.ndarray
The b vector in A x = b. This vector has length N.
sqivar :
numpy.ndarray
The reciprocal of the errors in
bvec
. The name comes from the square root of the inverse variance, which is what this is.amatrix :
numpy.ndarray
The matrix A in A x = b. The shape of this matrix is (N, M).
Initialize the object and perform initial computations.
Attributes Summary
acoeff
( ndarray
) The fit parameters, x,chi2
( float
) The \chi^2 value of the fit.covar
( ndarray
) The covariance matrix.dof
( int
) The degrees of freedom of the fit.var
( ndarray
) The variances of the fit.yfit
( ndarray
) The evaluated best-fit at each point.Attributes Documentation
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acoeff
¶ (
ndarray
) The fit parameters, x, in A x = b. This vector has length M.
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chi2
¶ (
float
) The \chi^2 value of the fit.
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covar
¶ (
ndarray
) The covariance matrix. The shape of this matrix is (M, M).
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dof
¶ (
int
) The degrees of freedom of the fit. This is the number of values ofbvec
that havesqivar
> 0 minus the number of fit paramaters, which is equal to M.
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var
¶ (
ndarray
) The variances of the fit. This is identical to the diagonal of the covariance matrix. This vector has length M.
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yfit
¶ (
ndarray
) The evaluated best-fit at each point. This vector has length N.
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