| Re: no backwards compatibility in IDL 5.6 [message #34260 is a reply to message #34259] |
Thu, 27 February 2003 07:56   |
Alexander Rauscher
Messages: 9
Registered: August 2001
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Junior Member |
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On Thu, 27 Feb 2003, James Kuyper wrote:
*Alexander Rauscher wrote:
*>
*> sorry for posting the same thing twice under different subjects, but i
*> think this is important...
*>
*> many of idl programs have to be adapted due do the non existing
*> backwards compatibility of atan (and probably many other functions) .
*> one wouldn't expect a change in such a fundamental function. so now
*> atan(z, /phase) gives the same result as atan(z) in older versions did,
*> where z is (re,im)... this is worse than stupid. this is dangerous.
*
*As you've described it, that doesn't qualify as an example of backwards
*incompatibility. If /phase is a new option with 5.6 (and it isn't
*mentioned in the online help for our 5.4 system), then there won't be
*any existing code using that option. Therefore, atan(z,/phase) could
*play Beethoven's 5th, and not be a violation of backwards compatibility.
*
*What would be an example of incompatibility, is if you need to provide
*the /phase option to get that behavior. Is that what you're saying? If
*so, I'd agree with you that it is stupid, and dangerous.
*
okay, maybe i didn't explain it correctly:
i do need to provide the keyword to to get the same results as in 5.4
e.g.: i have a complex mr image and i can look at the magnitude image:
tvscl, abs(image)
or at the phase image:
tvscl, atan(image) ; 5.4
tvscl, atan(image, /phase); 5.6
so any code written for 5.4 that uses atan() has to be changed to
atan( ,/phase) to work correctly in 5.6.
regards,
alex
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