Name

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DAOERF

Purpose

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Calulates the intensity, and derivatives, of a 2-d Gaussian PSF

Explanation

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Corrects for the finite size of a pixel by integrating the Gaussian
over the size of the pixel. Used in the IDL-DAOPHOT sequence.

Calling Sequence

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DAOERF, XIN, YIN, A, F, [ PDER ]

Inputs

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XIN - input scalar, vector or array, giving X coordinate values
YIN - input scalar, vector or array, giving Y coordinate values, must
have same number of elements as XIN.
A - 5 element parameter array describing the Gaussian
A(0) - peak intensity
A(1) - X position of peak intensity (centroid)
A(2) - Y position of peak intensity (centroid)
A(3) - X sigma of the gaussian (=FWHM/2.345)
A(4) - Y sigma of gaussian

Outputs

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F - array containing value of the function at each (XIN,YIN)
The number of output elements in F and PDER is identical with
the number of elements in X and Y

Optional Outputs

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PDER - 2 dimensional array of size (NPTS,5) giving the analytic
derivative at each value of F with respect to each parameter A.

Revision History

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Written: W. Landsman October, 1987
Converted to IDL V5.0 W. Landsman September 1997