cgdbltostr.pro
5.61 KB
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; docformat = 'rst'
;
; NAME:
; cgDBLTOSTR
;
; PURPOSE:
; This is a program for converting a double precision numerical value
; to a string that maintains the 14 double-precision significant digits.
;******************************************************************************************;
; ;
; Copyright (c) 2005-2012, 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. ;
;******************************************************************************************;
;+
; This is a program for converting a double precision numerical value
; to a string that maintains the 14 double-precision significant digits.
;
; :Categories:
; Utilities
;
; :Returns:
; A string value with the appropriate number of significant digits is returned.
;
; :Params:
; value: in, required
; A double-precision or floating point value that is to be converted to a string.
;
; :Examples:
; Here is how to use this program::
; IDL> Print, cgDblToStr(54.84392095433821d)
; 54.843920954338
;
; :Author:
; FANNING SOFTWARE CONSULTING::
; David W. Fanning
; 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
;
; :History:
; Change History::
; Written by BioPhys and offered to the IDL newsgroup, 7 November 2005.
; Slightly modified and renamed by David Fanning, 30 November, 2005.
; Retired as DblToStr and reincarnated it as cgDblToStr. 30 November, 2012. DWF.
;
; :Copyright:
; Copyright (c) 2005-2012, Fanning Software Consulting, Inc.
;-
FUNCTION cgDBLTOSTR, value
; Error handling.
On_Error, 2
IF N_Elements(value) EQ 0 THEN Message, 'Double precision or floaing value must be passed to the function.'
; Get the data type.
theType = Size(value, /Type)
IF theType NE 4 AND theType NE 5 THEN BEGIN
value = Double(value)
theType = 5
ENDIF
; Data extension.
typeExt = theType EQ 4 ? 'e' : 'd'
; Create a string, using the full-width G format.
rawstr = StrTrim(String(value, Format = '(g)'), 2)
; Extract the sign from the string and remove it for the moment.
sign = StrMid(rawstr, 0, 1) EQ '-' ? '-' : ''
rawstr = sign EQ '' ? rawstr:StrMid(rawstr, 1)
; Is there an exponent in the string? If so, remove that for the moment.
epos = StrPos(rawstr, 'e')
indx = epos gt -1 ? StrMid(rawstr, epos+1) : ''
rawstr = indx EQ '' ? rawstr:StrMid(rawstr, 0, epos)
; Find the position of the decimal point.
dpos = StrPos(rawstr, '.')
; Rounding process (assumes 14 significant digits).
outstr = StrArr(15)
FOR i = 0, 14 DO outstr[i] = StrMid(rawstr, i, 1)
aux = Fix(StrMid(rawstr, 16, 1)) GE 5?1:0
FOR i = 14, 0, -1 DO BEGIN
IF i NE dpos then BEGIN
sumstr = StrTrim(String(aux+fix(outstr[i])), 2)
sumlen = StrLen(sumstr)
outstr[i] = StrMid(sumstr, sumlen-1, 1)
aux = sumlen EQ 1 ? 0 : 1
ENDIF
ENDFOR
; Throw away '0's at the end.
ii = 14
WHILE outstr[ii] EQ '0' DO BEGIN
ii = ii-1
ENDWHILE
; Reconstruct the string.
saux = aux NE 0 ? '1' : ''
IF indx EQ "" THEN typeExt = ""
outstr = sign + saux + StrJoin(outstr[0:ii]) + typeExt + indx
; Return it.
RETURN, outstr
END