computechi2

class pydl.pydlutils.math.computechi2(bvec, sqivar, amatrix)

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

acoeff

(ndarray) The fit parameters, x, in A x = b. This vector has length M.

chi2

(float) The \chi^2 value of the fit.

covar

(ndarray) The covariance matrix. The shape of this matrix is (M, M).

dof

(int) The degrees of freedom of the fit. This is the number of values of bvec that have sqivar > 0 minus the number of fit paramaters, which is equal to M.

var

(ndarray) The variances of the fit. This is identical to the diagonal of the covariance matrix. This vector has length M.

yfit

(ndarray) The evaluated best-fit at each point. This vector has length N.