/usr/share/gnudatalanguage/coyote/cglineintersect.pro is in gdl-coyote 2016.11.13-2.
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;
; NAME:
; cgLineIntersect
;
; PURPOSE:
; This function returns the intersection of two line segments, represented by four points.
;
;******************************************************************************************;
; ;
; Copyright (c) 2014, 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 function returns the intersection of two line segments, represented by four points.
;
; :Categories:
; Utilities
;
; :Params:
; x0: in, required
; The x location of the one end of the first line segment.
; y0: in, required
; The y location of the one end of the first line segment.
; x1: in, required
; The x location of the other end of the first line segment.
; y1: in, required
; The y location of the other end of the first line segment.
; x2: in, required
; The x location of the one end of the second line segment.
; y2: in, required
; The y location of the one end of the second line segment.
; x3: in, required
; The x location of the other end of the second line segment.
; y3: in, required
; The y location of the other end of the second line segment.
;
; :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, 10 September 2014 on suggestion of Wang Kang.
;
; :Copyright:
; Copyright (c) 2014, Fanning Software Consulting, Inc.
;-
FUNCTION cgLineIntersect, x0, y0, x1, y1, x2, y2, x3, y3
param1 = LINFIT([x0, x1], [y0, y1])
param2 = LINFIT([x3, x2], [y3, y2])
x = [[param1[1]*(-1.), 1.],[param2[1]*(-1.), 1.]]
b = [[param1[0]],[param2[0]]]
intersection = b # Invert(x)
RETURN, intersection
END
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