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The `d T` (`calc-tex-language`

) command selects the conventions
of “math mode” in Donald Knuth's TeX typesetting language,
and the `d L` (`calc-latex-language`

) command selects the
conventions of “math mode” in LaTeX, a typesetting language that
uses TeX as its formatting engine. Calc's LaTeX language mode can
read any formula that the TeX language mode can, although LaTeX
mode may display it differently.

Formulas are entered and displayed in the appropriate notation;
‘`sin(a/b)`’
will appear as ‘`\sin\left( {a \over b} \right)`’ in TeX mode and
‘`\sin\left(\frac{a}{b}\right)`’ in LaTeX mode.
Math formulas are often enclosed by ‘`$ $`’ signs in TeX and
LaTeX; these should be omitted when interfacing with Calc. To Calc,
the ‘`$`’ sign has the same meaning it always does in algebraic
formulas (a reference to an existing entry on the stack).

Complex numbers are displayed as in ‘`3 + 4i`’. Fractions and
quotients are written using `\over`

in TeX mode (as in
`{a \over b}`

) and `\frac`

in LaTeX mode (as in
`\frac{a}{b}`

); binomial coefficients are written with
`\choose`

in TeX mode (as in `{a \choose b}`

) and
`\binom`

in LaTeX mode (as in `\binom{a}{b}`

).
Interval forms are written with `\ldots`

, and error forms are
written with `\pm`

. Absolute values are written as in
‘`|x + 1|`’, and the floor and ceiling functions are written with
`\lfloor`

, `\rfloor`

, etc. The words `\left`

and
`\right`

are ignored when reading formulas in TeX and LaTeX
modes. Both `inf`

and `uinf`

are written as `\infty`

;
when read, `\infty`

always translates to `inf`

.

Function calls are written the usual way, with the function name followed
by the arguments in parentheses. However, functions for which TeX
and LaTeX have special names (like `\sin`

) will use curly braces
instead of parentheses for very simple arguments. During input, curly
braces and parentheses work equally well for grouping, but when the
document is formatted the curly braces will be invisible. Thus the
printed result is
‘`sin 2x`’
but
‘`sin(2 + x)`’.

The TeX specific unit names (see Predefined Units) will not use
the ‘`tex`’ prefix; the unit name for a TeX point will be
‘`pt`’ instead of ‘`texpt`’, for example.

Function and variable names not treated specially by TeX and LaTeX
are simply written out as-is, which will cause them to come out in
italic letters in the printed document. If you invoke `d T` or
`d L` with a positive numeric prefix argument, names of more than
one character will instead be enclosed in a protective commands that
will prevent them from being typeset in the math italics; they will be
written ‘`\hbox{ name}`’ in TeX mode and
‘

`\`

during
reading have the `\`

removed. (Note that in this mode, long
variable names are still written with `\hbox`

or `\text`

.
However, you can always make an actual variable name like `\bar`

in
any TeX mode.)
During reading, text of the form ‘`\matrix{ ... }`’ is replaced
by ‘`[ ... ]`’. The same also applies to `\pmatrix`

and
`\bmatrix`

. In LaTeX mode this also applies to
‘`\begin{matrix} ... \end{matrix}`’,
‘`\begin{bmatrix} ... \end{bmatrix}`’,
‘`\begin{pmatrix} ... \end{pmatrix}`’, as well as
‘`\begin{smallmatrix} ... \end{smallmatrix}`’.
The symbol ‘`&`’ is interpreted as a comma,
and the symbols ‘`\cr`’ and ‘`\\`’ are interpreted as semicolons.
During output, matrices are displayed in ‘`\matrix{ a & b \\ c & d}`’
format in TeX mode and in
‘`\begin{pmatrix} a & b \\ c & d \end{pmatrix}`’ format in
LaTeX mode; you may need to edit this afterwards to change to your
preferred matrix form. If you invoke `d T` or `d L` with an
argument of 2 or −2, then matrices will be displayed in two-dimensional
form, such as

\begin{pmatrix} a & b \\ c & d \end{pmatrix}

This may be convenient for isolated matrices, but could lead to expressions being displayed like

\begin{pmatrix} \times x a & b \\ c & d \end{pmatrix}

While this wouldn't bother Calc, it is incorrect LaTeX. (Similarly for TeX.)

Accents like `\tilde`

and `\bar`

translate into function
calls internally (‘`tilde(x)`’, ‘`bar(x)`’). The `\underline`

sequence is treated as an accent. The `\vec`

accent corresponds
to the function name `Vec`

, because `vec`

is the name of
a built-in Calc function. The following table shows the accents
in Calc, TeX, LaTeX and eqn (described in the next section):

Calc TeX LaTeX eqn ---- --- ----- --- acute \acute \acute Acute \Acute bar \bar \bar bar Bar \Bar breve \breve \breve Breve \Breve check \check \check Check \Check dddot \dddot ddddot \ddddot dot \dot \dot dot Dot \Dot dotdot \ddot \ddot dotdot DotDot \Ddot dyad dyad grave \grave \grave Grave \Grave hat \hat \hat hat Hat \Hat Prime prime tilde \tilde \tilde tilde Tilde \Tilde under \underline \underline under Vec \vec \vec vec VEC \Vec

The ‘`=>`’ (evaluates-to) operator appears as a `\to`

symbol:
‘`{ a \to b}`’. TeX defines

`\to`

as an
alias for `\rightarrow`

. However, if the ‘`\evalto`

word is ignored by Calc's input routines, and is undefined in TeX.
You will typically want to include one of the following definitions
at the top of a TeX file that uses `\evalto`

:
\def\evalto{} \def\evalto#1\to{}

The first definition formats evaluates-to operators in the usual
way. The second causes only the `b` part to appear in the
printed document; the `a` part and the arrow are hidden.
Another definition you may wish to use is ‘`\let\to=\Rightarrow`’
which causes `\to`

to appear more like Calc's ‘`=>`’ symbol.
See Evaluates-To Operator, for a discussion of `evalto`

.

The complete set of TeX control sequences that are ignored during reading is:

\hbox \mbox \text \left \right \, \> \: \; \! \quad \qquad \hfil \hfill \displaystyle \textstyle \dsize \tsize \scriptstyle \scriptscriptstyle \ssize \ssize \rm \bf \it \sl \roman \bold \italic \slanted \cal \mit \Cal \Bbb \frak \goth \evalto

Note that, because these symbols are ignored, reading a TeX or LaTeX formula into Calc and writing it back out may lose spacing and font information.

Also, the “discretionary multiplication sign” ‘`\*`’ is read
the same as ‘`*`’.

The TeX version of this manual includes some printed examples at the end of this section.