1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html40/loose.dtd">
<HTML>
<!-- Created on May, 18 2005 by texi2html 1.66 -->
<!--
Written by: Lionel Cons <Lionel.Cons@cern.ch> (original author)
Karl Berry <karl@freefriends.org>
Olaf Bachmann <obachman@mathematik.uni-kl.de>
and many others.
Maintained by: Many creative people <dev@texi2html.cvshome.org>
Send bugs and suggestions to <users@texi2html.cvshome.org>
-->
<HEAD>
<TITLE>GNU Octave: Data Types</TITLE>
<META NAME="description" CONTENT="GNU Octave: Data Types">
<META NAME="keywords" CONTENT="GNU Octave: Data Types">
<META NAME="resource-type" CONTENT="document">
<META NAME="distribution" CONTENT="global">
<META NAME="Generator" CONTENT="texi2html 1.66">
</HEAD>
<BODY LANG="en" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#800080" ALINK="#FF0000">
<A NAME="SEC42"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_3.html#SEC41"> < </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC43"> > </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_3.html#SEC24"> << </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave.html#SEC_Top"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_5.html#SEC50"> >> </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_toc.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_42.html#SEC245">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_abt.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H1> 3. Data Types </H1>
<!--docid::SEC42::-->
<P>
All versions of Octave include a number of built-in data types,
including real and complex scalars and matrices, character strings, and
a data structure type.
</P>
<P>
It is also possible to define new specialized data types by writing a
small amount of C++ code. On some systems, new data types can be loaded
dynamically while Octave is running, so it is not necessary to recompile
all of Octave just to add a new type. See section <A HREF="octave_14.html#SEC106">13.8 Dynamically Linked Functions</A>, for more information about Octave's dynamic linking
capabilities. <A HREF="octave_4.html#SEC48">3.2 User-defined Data Types</A> describes what you must do
to define a new data type for Octave.
</P>
<P>
<A NAME="doc-typeinfo"></A>
<A NAME="IDX73"></A>
</P>
<DL>
<DT><U>Built-in Function:</U> <B>typeinfo</B> <I>(<VAR>expr</VAR>)</I>
<DD><P>
Return the type of the expression <VAR>expr</VAR>, as a string. If
<VAR>EXPR</VAR> is omitted, return an array of strings containing all the
currently installed data types.
</P>
</DL>
<P>
<TABLE BORDER="0" CELLSPACING="0">
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="octave_4.html#SEC43">3.1 Built-in Data Types</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="octave_4.html#SEC48">3.2 User-defined Data Types</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="octave_4.html#SEC49">3.3 Object Sizes</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
</TABLE>
<P>
<A NAME="Built-in Data Types"></A>
<HR SIZE="6">
<A NAME="SEC43"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC42"> < </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC44"> > </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC42"> << </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC42"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_5.html#SEC50"> >> </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_toc.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_42.html#SEC245">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_abt.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H2> 3.1 Built-in Data Types </H2>
<!--docid::SEC43::-->
<P>
The standard built-in data types are real and complex scalars and
matrices, ranges, character strings, and a data structure type.
Additional built-in data types may be added in future versions. If you
need a specialized data type that is not currently provided as a
built-in type, you are encouraged to write your own user-defined data
type and contribute it for distribution in a future release of Octave.
</P>
<P>
<TABLE BORDER="0" CELLSPACING="0">
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="octave_4.html#SEC44">3.1.1 Numeric Objects</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="octave_4.html#SEC45">3.1.2 Missing Data</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="octave_4.html#SEC46">3.1.3 String Objects</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="octave_4.html#SEC47">3.1.4 Data Structure Objects</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
</TABLE>
<P>
<A NAME="Numeric Objects"></A>
<HR SIZE="6">
<A NAME="SEC44"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC43"> < </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC45"> > </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC42"> << </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC43"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_5.html#SEC50"> >> </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_toc.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_42.html#SEC245">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_abt.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H3> 3.1.1 Numeric Objects </H3>
<!--docid::SEC44::-->
<P>
Octave's built-in numeric objects include real and complex scalars and
matrices. All built-in numeric data is currently stored as double
precision numbers. On systems that use the IEEE floating point format,
values in the range of approximately
2.2251e-308 to 1.7977e+308
can be stored, and the relative precision is approximately
2.2204e-16.
The exact values are given by the variables <CODE>realmin</CODE>,
<CODE>realmax</CODE>, and <CODE>eps</CODE>, respectively.
</P>
<P>
Matrix objects can be of any size, and can be dynamically reshaped and
resized. It is easy to extract individual rows, columns, or submatrices
using a variety of powerful indexing features. See section <A HREF="octave_11.html#SEC73">10.1 Index Expressions</A>.
</P>
<P>
See section <A HREF="octave_5.html#SEC50">4. Numeric Data Types</A>, for more information.
</P>
<P>
<A NAME="Missing Data"></A>
<HR SIZE="6">
<A NAME="SEC45"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC44"> < </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC46"> > </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC42"> << </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC43"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_5.html#SEC50"> >> </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_toc.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_42.html#SEC245">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_abt.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H3> 3.1.2 Missing Data </H3>
<!--docid::SEC45::-->
<P>
<A NAME="doc-NA"></A>
<A NAME="IDX74"></A>
</P>
<DL>
<DT><U>Built-in Variable:</U> <B>NA</B>
<DD>Missing value.
</DL>
<P>
<A NAME="doc-isna"></A>
<A NAME="IDX75"></A>
</P>
<DL>
<DT><U>Mapping Function:</U> <B>isna</B> <I>(<VAR>x</VAR>)</I>
<DD>Return 1 for elements of <VAR>x</VAR> that are NA (missing) values and zero
otherwise. For example,
<P>
<TABLE><tr><td> </td><td class=example><pre>is_NA ([13, Inf, NA, NaN])
=> [ 0, 0, 1, 0 ]
</pre></td></tr></table></DL>
<P>
<A NAME="doc-is_nan_or_na"></A>
<A NAME="IDX76"></A>
</P>
<DL>
<DT><U>Mapping Function:</U> <B>is_nan_or_na</B> <I>(<VAR>x</VAR>)</I>
<DD>Return 1 for elements of <VAR>x</VAR> that are NaN or NA (missing) values
and zero otherwise. For example,
<P>
<TABLE><tr><td> </td><td class=example><pre>is_NAN_or_NA ([13, Inf, NA, NaN])
=> [ 0, 0, 1, 1 ]
</pre></td></tr></table></DL>
<P>
<A NAME="String Objects"></A>
<HR SIZE="6">
<A NAME="SEC46"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC45"> < </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC47"> > </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC42"> << </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC43"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_5.html#SEC50"> >> </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_toc.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_42.html#SEC245">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_abt.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H3> 3.1.3 String Objects </H3>
<!--docid::SEC46::-->
<P>
A character string in Octave consists of a sequence of characters
enclosed in either double-quote or single-quote marks. Internally,
Octave currently stores strings as matrices of characters. All the
indexing operations that work for matrix objects also work for strings.
</P>
<P>
See section <A HREF="octave_6.html#SEC56">5. Strings</A>, for more information.
</P>
<P>
<A NAME="Data Structure Objects"></A>
<HR SIZE="6">
<A NAME="SEC47"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC46"> < </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC48"> > </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC42"> << </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC43"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_5.html#SEC50"> >> </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_toc.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_42.html#SEC245">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_abt.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H3> 3.1.4 Data Structure Objects </H3>
<!--docid::SEC47::-->
<P>
Octave's data structure type can help you to organize related objects of
different types. The current implementation uses an associative array
with indices limited to strings, but the syntax is more like C-style
structures.
</P>
<P>
See section <A HREF="octave_7.html#SEC61">6. Data Structures</A>, for more information.
</P>
<P>
<A NAME="User-defined Data Types"></A>
<HR SIZE="6">
<A NAME="SEC48"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC47"> < </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC49"> > </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC42"> << </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC42"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_5.html#SEC50"> >> </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_toc.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_42.html#SEC245">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_abt.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H2> 3.2 User-defined Data Types </H2>
<!--docid::SEC48::-->
<P>
Someday I hope to expand this to include a complete description of
Octave's mechanism for managing user-defined data types. Until this
feature is documented here, you will have to make do by reading the code
in the `<TT>ov.h</TT>', `<TT>ops.h</TT>', and related files from Octave's
`<TT>src</TT>' directory.
</P>
<P>
<A NAME="Object Sizes"></A>
<HR SIZE="6">
<A NAME="SEC49"></A>
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC48"> < </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_5.html#SEC50"> > </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC42"> << </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC42"> Up </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_5.html#SEC50"> >> </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_toc.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_42.html#SEC245">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_abt.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<H2> 3.3 Object Sizes </H2>
<!--docid::SEC49::-->
<P>
The following functions allow you to determine the size of a variable or
expression. These functions are defined for all objects. They return
-1 when the operation doesn't make sense. For example, Octave's
data structure type doesn't have rows or columns, so the <CODE>rows</CODE> and
<CODE>columns</CODE> functions return -1 for structure arguments.
</P>
<P>
<A NAME="doc-columns"></A>
<A NAME="IDX77"></A>
</P>
<DL>
<DT><U>Function File:</U> <B>columns</B> <I>(<VAR>a</VAR>)</I>
<DD>Return the number of columns of <VAR>a</VAR>.
</DL>
<P>
<A NAME="doc-rows"></A>
<A NAME="IDX78"></A>
</P>
<DL>
<DT><U>Function File:</U> <B>rows</B> <I>(<VAR>a</VAR>)</I>
<DD>Return the number of rows of <VAR>a</VAR>.
</DL>
<P>
<A NAME="doc-length"></A>
<A NAME="IDX79"></A>
</P>
<DL>
<DT><U>Built-in Function:</U> <B>length</B> <I>(<VAR>a</VAR>)</I>
<DD>Return the `length' of the object <VAR>a</VAR>. For matrix objects, the
length is the number of rows or columns, whichever is greater (this
odd definition is used for compatibility with Matlab).
</DL>
<P>
<A NAME="doc-size"></A>
<A NAME="IDX80"></A>
</P>
<DL>
<DT><U>Built-in Function:</U> <B>size</B> <I>(<VAR>a</VAR>, <VAR>n</VAR>)</I>
<DD>Return the number rows and columns of <VAR>a</VAR>.
<P>
With one input argument and one output argument, the result is returned
in a row vector. If there are multiple output arguments, the number of
rows is assigned to the first, and the number of columns to the second,
etc. For example,
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>size ([1, 2; 3, 4; 5, 6])
=> [ 3, 2 ]
[nr, nc] = size ([1, 2; 3, 4; 5, 6])
=> nr = 3
=> nc = 2
</pre></td></tr></table><P>
If given a second argument, <CODE>size</CODE> will return the size of the
corresponding dimension. For example
</P>
<P>
<TABLE><tr><td> </td><td class=example><pre>size ([1, 2; 3, 4; 5, 6], 2)
=> 2
</pre></td></tr></table><P>
returns the number of columns in the given matrix.
</P>
</DL>
<P>
<A NAME="doc-isempty"></A>
<A NAME="IDX81"></A>
</P>
<DL>
<DT><U>Built-in Function:</U> <B>isempty</B> <I>(<VAR>a</VAR>)</I>
<DD>Return 1 if <VAR>a</VAR> is an empty matrix (either the number of rows, or
the number of columns, or both are zero). Otherwise, return 0.
</DL>
<P>
<A NAME="Numeric Data Types"></A>
<HR SIZE="6">
<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_4.html#SEC42"> << </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_5.html#SEC50"> >> </A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave.html#SEC_Top">Top</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_toc.html#SEC_Contents">Contents</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_42.html#SEC245">Index</A>]</TD>
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="octave_abt.html#SEC_About"> ? </A>]</TD>
</TR></TABLE>
<BR>
<FONT SIZE="-1">
This document was generated
by <I>John W. Eaton</I> on <I>May, 18 2005</I>
using <A HREF="http://texi2html.cvshome.org"><I>texi2html</I></A>
</FONT>
</BODY>
</HTML>
|
