
## Section19Pre-Formatted Text

In Sage, if you wanted to build a matrix, then you would use the matrix() constructor. Here is the matrix of second partials of $f(x,y)=x^3+8x^2y^3 + y^4\text{,}$ as you would enter it in Sage. Notice that SR is the ring of symbolic expressions, Symbolic Ring.

var('x', 'y')
J = matrix(SR, [
[6*x + 16*y^3, 48*x*y^2],
[48*x*y^2, 48*x^2*y + 12*y^2]
])


That accomplished, Sage will easily and naturally provide a representation of the matrix with the command latex(J).

\left(\begin{array}{rr}
16 \, y^{3} + 6 \, x & -48 \, x y^{2} \\
48 \, x y^{2} & 48 \, x^{2} y + 12 \, y^{2}
\end{array}\right)


The realization of preformatted text should be robust enough that it can be cut from documents and pasted without any substitutions of “fancier” Unicode characters for generic ASCII characters. Try the “minus” sign on the $48$ above to see if it does not become a dash, or the single quotes on the Sage variables.

For Sage input code, the first non-whitespace character sets the left margin, since legitimate Python code has no subsequent lines outdented. For pre-formatted code, the line with the least whitespace leading the line will determine the left margin. If preserving indentation is important, do not mix spaces and tabs. For syntax highlighting of text representing computer programs, or parts of them, see Section 20. Examine the source of the following example to help understand this paragraph.

        A normal line
An indented line
An outdented line


Snippets should also be robust for cut/paste operations. For example, you should not get “curly” “smart” quote marks in verbatim text: this should have "dumb" quote marks. Here are a few characters that should migrate through to a PDF unmolested: '"----"'

If you write a very long snippet of inline code it can impinge on the right margin, since very long words will not hypenate, unless you have a dash/hypen. Such as when you use words like pneumonoultramicroscopicsilicovolcanoconiosis, parastratiosphecomyia stratiosphecomyioides, floccinaucinihilipilification, or subdermatoglyphic. For output in LaTeX we get line-breaking, and perhaps word-spacing, but we do not get hyphenation and the font is fixed-width. So not always perfect. Consider other options like <cd> or <pre> below.

An intermediate type of verbatim text can be accomplished with the <cd> tag, short for “code display.” It allows for larger chunks of verbatim text to show up in the middle of a paragraph, but with some vertical space above and below. It can be

authored as a single line

or if you wish to have multiple lines

there is the cline tag
meant to model the line tag
and short for "code line"


and you may even

use a single cline


if you like to have your source closely model the visual look of the output.

The <pre> tag is meant for use outside of paragraphs, but is otherwise very similar. The source may also be structured as a sequence of <cline> as in the next example, recycling content from above.

If you write a very long snippet of inline code it
can impinge on the right margin, since very long words
will not hypenate, unless you have a dash/hypen.  Such
as when you use words like
pneumonoultramicroscopicsilicovolcanoconiosis,
parastratiosphecomyia stratiosphecomyioides,
floccinaucinihilipilification, or subdermatoglyphic.
For output in LaTeX we get line-breaking, and perhaps
word-spacing, but we do not get hyphenation and the
font is fixed-width.  So not always perfect.  Consider
other options like <cd> or <pre> below.