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odd behaviour from array_equal() with NaN, Inf values [message #79039]

Sun, 22 January 2012 20:42

wallabadah
Messages: 28
Registered: November 2005

Junior Member

I've come across the following behaviour while tracking down odd behaviour from NaN and Inf values. I'm trying to use array_equal() to check that arrays contain the same content - but it bombs when the arrays contain NaN. I've tracked it down to the process of copying an array containing NaN values to a new variable. For example:

IDL> a = findgen(5)
IDL> a[1] = !values.f_nan
IDL> print, array_equal(a, a)
1
IDL> b = a
IDL> print, array_equal(a, b)
0
IDL> print, array_equal(b, b)
1

Repeating the process with !values.f_infinity behaves as expected:

IDL> a = findgen(5)
IDL> a[1] = !values.f_infinity
IDL> print, array_equal(a, a)
1
IDL> b = a
IDL> print, array_equal(a, b)
1
IDL> print, array_equal(b, b)
1

Is this a bug in make_array() or some artifact of how values are copied to new variables?? Is it reproducible on different platforms (I'm on Mac OS X, IDL 8.1).

thanks in advance,

Will

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odd behaviour from array_equal() with NaN, Inf values

By: wallabadah on Sun, 22 January 2012 20:42

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