fpufix.pro
5.14 KB
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;+
; NAME:
; FPUFIX
;
; PURPOSE:
;
; This is a utility routine to examine a variable and fix problems
; that will create floating point underflow errors.
;
; AUTHOR:
;
; FANNING SOFTWARE CONSULTING
; David Fanning, Ph.D.
; 1645 Sheely Drive
; Fort Collins, CO 80526 USA
; Phone: 970-221-0438
; E-mail: david@idlcoyote.com
; Coyote's Guide to IDL Programming: http://www.idlcoyote.com
;
; CATEGORY:
;
; Utilities
;
; CALLING SEQUENCE:
;
; fixedData = FPUFIX(data)
;
; ARGUMENTS:
;
; data : A numerical variable to be checked for values that will cause
; floating point underflow errors. Suspect values are set to 0.
;
; KEYWORDS:
;
; None.
; RETURN VALUE:
;
; fixedData: The output is the same as the input, except that any values that
; will cause subsequent floating point underflow errors are set to 0.
;
; COMMON BLOCKS:
; None.
;
; EXAMPLES:
;
; data = FPTFIX(data)
;
; RESTRICTIONS:
;
; None.
;
; MODIFICATION HISTORY:
;
; Written by David W. Fanning, from Mati Meron's example FPU_FIX. Mati's
; program is more robust that this (ftp://cars3.uchicago.edu/midl/),
; but this serves my needs and doesn't require other programs from
; Mati's library. 24 February 2006.
;-
;******************************************************************************************;
; Copyright (c) 2008, by Fanning Software Consulting, Inc. ;
; All rights reserved. ;
; ;
; Redistribution and use in source and binary forms, with or without ;
; modification, are permitted provided that the following conditions are met: ;
; ;
; * Redistributions of source code must retain the above copyright ;
; notice, this list of conditions and the following disclaimer. ;
; * Redistributions in binary form must reproduce the above copyright ;
; notice, this list of conditions and the following disclaimer in the ;
; documentation and/or other materials provided with the distribution. ;
; * Neither the name of Fanning Software Consulting, Inc. nor the names of its ;
; contributors may be used to endorse or promote products derived from this ;
; software without specific prior written permission. ;
; ;
; THIS SOFTWARE IS PROVIDED BY FANNING SOFTWARE CONSULTING, INC. ''AS IS'' AND ANY ;
; EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES ;
; OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT ;
; SHALL FANNING SOFTWARE CONSULTING, INC. BE LIABLE FOR ANY DIRECT, INDIRECT, ;
; INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED ;
; TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; ;
; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ;
; ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ;
; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS ;
; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. ;
;******************************************************************************************;
FUNCTION FPUFIX, data
; Return to caller on error after setting !Except.
On_Error, 2
Catch, theError
IF theError NE 0 THEN BEGIN
Catch, /Cancel
Message, !Error_State.Msg
IF N_Elements(except) THEN !EXCEPT = except
RETURN, data
ENDIF
; Only want to deal with numerical data types.
; Return all other kinds.
dataType = Size(data, /Type)
nogoodtypes = [0,7,8,10,11]
void = Where(nogoodTypes EQ dataType, count)
IF count GT 0 THEN RETURN, data
; Floating underflow error we are trying to fix.
fpu_error = 32
; Save current !EXCEPT. Don't report exceptions here.
except = !EXCEPT
!EXCEPT = 1
; Clear math error status.
void = Check_Math()
; Do something with the data that will cause floating underflow errors.
void = Min(data, /NAN)
; Check the math error status now.
check = Check_Math()
; If this is a floating underflow error, then fix it.
IF check EQ fpu_error THEN BEGIN
info = MaChar(DOUBLE=(dataType EQ 5 OR dataType EQ 9))
indices = Where(Abs(data) LT info.xmin, count)
IF count GT 0 THEN data[indices] = 0
ENDIF
; Clean up.
!EXCEPT = except
void = Check_Math()
; Return the repaired data.
RETURN, data
END