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3<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
4  <head>
5    <title>lineintersection.pro (SAXO Documentation Assistant)</title>
6  </head>
7
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50<font size=-1><i>SAXO Documentation Assistant</i>: <a href="./../home.html">Overview</a></font></td>
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56
57    <h1><font size="-2">Utilities/</font></h1>
58    <h2>lineintersection.pro</h2>
59
60    <dl>
61    </dl>
62
63   
64 Calculate coordinates of the intersection between 2 straight lines
65 or of a succession of 2 straight lines.
66
67
68   
69
70     
71      <a name="#_lineintersection"></a>
72
73      <h2>lineintersection  <font size="-1" color="#006633">
74 Utilities
75</font></h2>
76
77      <p><font face="Courier"><i>result = </i>lineintersection(<i><a href="#_lineintersection_keyword_abc1">abc1</a>, <a href="#_lineintersection_keyword_abc2">abc2</a></i>, <a href="#_lineintersection_keyword_FLOAT">FLOAT</a>=<i>FLOAT</i>)</font></p>
78
79   
80
81
82    <h3>Return value</h3>
83 2 possibilities:
84      1) by default: it is a vector of complex whose each element is the coordinates
85                     of the intersection point of a pair of straight lines.
86      2) if FLOAT is activated, it is a array of reals of dimension 2,
87         number_of_pairs_of_straight_lines whose each row is the coordinates
88         of the intersection point of a pair of straight line.
89
90
91   
92    <h3>Parameters</h3>
93   
94
95    <a name="#_lineintersection_keyword_abc1"></a>
96    <h4>abc1&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
97      <font size="-1" color="#006633">in</font>
98     
99     
100      <font size="-1" color="#006633">required</font>
101     
102      <font size="-1" color="#006633">type:</font> <font size="-1" color="#006633"><i>3d array</i></font>
103     
104     
105    </h4>
106
107   
108 is the first array of dimension 3, number_of_pairs_of_straight_lines,
109 whose each line contain the 3 parameters a, b and c of the first linear
110 equation of the type ax+by+c=0
111
112   
113
114    <a name="#_lineintersection_keyword_abc2"></a>
115    <h4>abc2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
116      <font size="-1" color="#006633">in</font>
117     
118     
119      <font size="-1" color="#006633">required</font>
120     
121      <font size="-1" color="#006633">type:</font> <font size="-1" color="#006633"><i>3d array</i></font>
122     
123     
124    </h4>
125
126   
127 is second array of dimension 3, number_of_pairs_of_straight_lines,
128 whose each line contain the 3 parameters a, b and c of the second linear
129 equation of the type ax+by+c=0
130
131   
132   
133
134   
135    <h3>Keywords</h3>
136
137   
138    <a name="#_lineintersection_keyword_FLOAT"></a>
139    <h4>FLOAT&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
140     
141     
142     
143     
144     
145     
146     
147     
148    </h4>
149
150   
151 To return the output as a array of real numbers instead of vectors of
152 complex (by default)
153
154   
155   
156
157    <h3>Examples</h3><pre>
158 IDL> abc1=linearequation(complex(1,2),[3,4])
159 IDL> abc2=linearequation(complex(1,2),[8,15])
160 IDL> print, lineintersection(abc1, abc2)
161 (      1.00000,      2.00000)
162 IDL> print, lineintersection(abc1, abc2,/float)
163 1.00000      2.00000
164
165    </pre><h3>Version history</h3>
166   
167    <h4>Version</h4>
168 $Id: lineintersection.pro 327 2007-12-13 16:22:35Z pinsard $
169
170    <h4>History</h4>
171 Sebastien Masson (smasson@lodyc.jussieu.fr)
172          10 juin 2000
173
174   
175
176    <h3>Known issues</h3>
177   
178   
179   
180    <h4>Restrictions</h4>
181 If the 2 straight lines are parallel, we return coordinates
182 (!values.f_nan,!values.f_nan)
183
184 Beware of the precision of the machine which make
185 that calculated coordinates may not exactly verify
186 equations of the pair of straight lines.
187
188
189   
190   
191   
192   
193   
194   
195   
196
197    <font size="-3"><p>&nbsp;</p></font>
198    <hr size="1" color="#CCCCCC"/>
199     
200
201   
202
203    <p><font color="gray" size="-3">&nbsp;&nbsp;Produced by IDLdoc 2.0.</font></p>
204
205  </body>
206</html>
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