15.2.7 Use of the interpreter Property

All text objects—such as titles, labels, legends, and text—include the property "interpreter", this property determines the manner in which special control sequences in the text are rendered. If the interpreter is set to "none", then no rendering occurs. Currently the "latex" interpreter is not implemented and is equivalent to "none".

The "tex" option implements a subset of TeX functionality when rendering text. This allows the insertion of special glyphs such as Greek characters or mathematical symbols. The special characters are inserted with a code following a backslash (\) character, as in the table Table 15.1.

In addition, the formatting of the text can be changed within the string by using the codes

These may be used in conjunction with the { and } characters to limit the change in the font to part of the string. For example,

xlabel ('{\bf H} = a {\bf V}')

where the character 'a' will not appear in a bold font. Note that to avoid having Octave interpret the backslash characters in the strings, the strings should be in single quotes.

It is also possible to change the fontname and size within the text

Finally, superscripting and subscripting can be controlled with the '^' and '_' characters. If the '^' or '_' is followed by a { character, then all of the block surrounded by the { } pair is super- or sub-scripted. Without the { } pair, only the character immediately following the '^' or '_' is super- or sub-scripted.

A complete example showing the capabilities of the extended text is

x = 0:0.01:3;
plot (x, erf (x));
hold on;
plot (x,x,"r");
axis ([0, 3, 0, 1]);
text (0.65, 0.6175, strcat ('\leftarrow x = {2/\surd\pi',
' {\fontsize{16}\int_{\fontsize{8}0}^{\fontsize{8}x}}',
' e^{-t^2} dt} = 0.6175'))

The result of which can be seen in Figure 15.7

Figure 15.7: Example of inclusion of text with the TeX interpreter