| TOTAL() and NaNs, again [message #83737] |
Mon, 25 March 2013 14:30 |
Fabzi
Messages: 305
Registered: July 2010
|
Senior Member |
|
|
Dear IDLers,
I know my problems with NaNs do bother just my little person. Maybe I am
the only one having crappy data to deal with, or I am the only one using
NaNs to mask out things in my 3D data arrays... Anyways, I'll try to
make this is my last post about NaNs.
I've been complaining lately about MEAN throwing a math error in this case:
IDL> array = [!VALUES.F_NAN, !VALUES.F_NAN]
IDL> print, MEAN(array, /NAN)
-NaN
% Program caused arithmetic error: Floating illegal operand
I think, personally, that the result of mean in this case should be a
NaN, and that this should not throw a math error. Because, afterwards,
if I do:
IDL> print, (array[0] + array[1]) / 0.
NaN
This is an ugly divide by zero but there is no math warning here. But
the problems comes from TOTAL:
IDL> print, TOTAL(array, /NAN)
0.00000
And of course:
IDL> print, TOTAL(array, /NAN) / TOTAL(FINITE(array))
-NaN
% Program caused arithmetic error: Floating illegal operand
To be honest, this is described in the Doc: "Since the value NaN is
treated as missing data, if Array contains only NaN values the TOTAL
routine will return 0."
But I don't see why it is so. This is not coherent with what one would
expect TOTAL to do: the sum of all the elements in the array...
Anyone to convince me that TOTAL() *has* to return 0 in this case?
Thanks ;-)
Fab
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
