| overplotting data and contours for small images [message #3828] |
Fri, 17 March 1995 02:04 |
lucio
Messages: 5
Registered: December 1993
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Junior Member |
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Hello,
I have a 16x16 matrix ima.data (which contains a chi-square map)
which has been generated by "fit stepping" on two parameters.
I know that my parameters range from 10 to 13 and to 142 to 145 (there
are 16 steps of 0.2 on each axis).
Therefore I plot with :
xar=findgen(16)*0.2+10
yar=findgen(16)*0.2+142
contour,ima.data,xar,yar,levels=[0,2.3,4.61,9.21],xrange=[10 ,13],yrange=[142,145]
(the levels are the usual 68%, 90% and 99% confidence contours).
What I get is that IN THE PLOT the centre of the contours (i.e. the minimum
of the image) is located 2 steps left in x (i.e -0.4 from the real x) and
2 steps up in y (i.e. +0.4 from the real y).
How does "contour" correlate positions in the image with the x and y
arrays ? Are there any artifact due to the fact my images have a small
number of pixels ?
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A member of G.ASS : Group for Astronomical Software Support
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Lucio Chiappetti - IFCTR/CNR | Ma te' vugl' da' quost avis a ti' Orsign
via Bassini 15 - I-20133 Milano | Buttet rabios intant te se' pisnign
Internet: LUCIO@IFCTR.MI.CNR.IT |
Decnet: IFCTR::LUCIO | (Rabisch, II 46, 119-120)
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