LatexPrint
Print Julia objects in LaTeX form.
Installation
Enter the package manager by typing a close bracket: ]
and then
pkg> add LatexPrint
Key functions
This module provides functions for converting Julia objects into
string representations for use in LaTeX mathematics mode. The primary
function is laprintln
which behaves precisely like println
except
Julia objects are first converted to a form suitable for
LaTeX. Because laprintln
is a lot to type, we also provide the
abbreviation lap
.
julia> using LatexPrint
julia> x = 2//6
1//3
julia> lap(x)
\frac{1}{3}
We also provide the function laprint
which does not append a new
line (just like print
).
These functions rely on latex_form
which converts a Julia object
into an String
representation in its LaTeX form:
julia> latex_form(x)
"\\frac{1}{3}"
The double backslash in the output of latex_form
is converted to a
single backslash when run through a print
function.
Supported Types
Numbers
Integers and floating point numbers
FloatingPoint
and Integer
numbers are printed unchanged.
julia> lap(sqrt(2))
1.4142135623730951
julia> lap(23)
23
However, infinite and invalid values are printed as follows:
julia> lap(1/0)
\infty
julia> lap(1/0)
\infty
julia> lap(0/0)
\text{NaN}
Julia's MathConst
numbers are printed using their expected LaTeX
form:
julia> lap(pi)
\pi
Rational numbers
Rational numbers are printed as fractions (unless the denominator happens to be 1, in which case we print as an integer).
julia> lap(10//4)
\frac{5}{2}
julia> lap(10//2)
5
Complex numbers
Complex numbers always include a real and an imaginary part, even if either part equals zero:
julia> z = 1+im
1 + 1im
julia> lap(z)
1+1i
julia> lap(z*z)
0+2i
julia> lap(im^im)
0.20787957635076193+0.0i
Boolean values
The Bool
values true
and false
output like this:
julia> lap(true)
\mathrm{T}
julia> lap(false)
\mathrm{F}
nothing
A nothing
value is rendered as \mathrm{nothing}
.
Text
The LaTeX version of an String
is wrapped in the command
\text
(which requires the amsmath
package in LaTeX). The rationale
is that we always want to able to paste the output of lap
directly
into mathematics mode in LaTeX.
julia> lap("Hello, world!")
\text{Hello, world!}
Arrays
Vectors (onedimensional arrays) and matrices (twodimensional arrays)
are converted into LaTeX array
environments bounded by square
brackets with centering alignment. (These default options can be
changed; see "Customizing existing types" later in this document.)
julia> x = [1,2,3]
3element Array{Int64,1}:
1
2
3
julia> lap(x)
\left[
\begin{array}{c}
1 \\
2 \\
3 \\
\end{array}
\right]
julia> A = eye(3)
3x3 Array{Float64,2}:
1.0 0.0 0.0
0.0 1.0 0.0
0.0 0.0 1.0
julia> lap(A)
\left[
\begin{array}{ccc}
1.0 & 0.0 & 0.0 \\
0.0 & 1.0 & 0.0 \\
0.0 & 0.0 & 1.0 \\
\end{array}
\right]
Vectors are, by default, rendered as a column. To typeset a vector as a row, simply take its transpose:
julia> x = [2//3, 4//3, 6//3]
3element Array{Rational{Int64},1}:
2//3
4//3
2//1
julia> lap(x')
\left[
\begin{array}{ccc}
\frac{2}{3} & \frac{4}{3} & 2 \\
\end{array}
\right]
Sets
Julia Set
and IntSet
objects are rendered as a comma separated
list between curly braces. The elements are sorted into ascending
order (if possible). An empty set is returned as \emptyset
(unless
another form is specified using set_empty
).
julia> A = Set({3.5, 2, 5})
Set{Any}({2,5,3.5})
julia> lap(A)
\left\{5,2,3.5\right\}
julia> B = IntSet(4,5,1)
IntSet([1, 4, 5])
julia> lap(B)
\left\{1,4,5\right\}
julia> C = Set()
Set{Any}({})
julia> lap(C)
\emptyset
tabular
function
The If A
is a matrix (twodimensional array), then laprintln(A)
(or
lap(A)
) prints the LaTeX code for that matrix (complete with
bounding delimeters) for inclusion in LaTeX's mathematics mode.
As an alternative, we also provide the function tabular
that prints
the array for inclusion in LaTeX's text mode in the tabular
environment.
julia> A = Array{Any}(nothing,2,2);
julia> A[1,1] = 1; A[1,2] = 3+im; A[2,1]=5//2; A[2,2] = 1/0;
julia> tabular(A)
\begin{tabular}{cc}
$1$ & $3+1i$\\
$\frac{5}{2}$ & $\infty$
\end{tabular}
Notice that each entry is encased in dollar signs.
By default, each column is center aligned. This can be modified in
two ways. See the set_align
function described below or by calling
tabular
with the named alignment
argument, like this:
julia> tabular(A,alignment="lr")
\begin{tabular}{lr}
$1$ & $3+1i$\\
$\frac{5}{2}$ & $\infty$
\end{tabular}
In addition, the endofline command \\
can be changed to
\\ \hline
(so LaTeX inserts a horizontal line between rows)
by means of the named hlines
argument:
julia> tabular(A,hlines=true)
\begin{tabular}{cc}
$1$ & $3+1i$\\ \hline
$\frac{5}{2}$ & $\infty$
\end{tabular}
Note that the last row of the array does not include an \hline
.
Customization
Customizing existing types
The LatexPrint
module comes with default LaTeX representations for
infinity, notanumber, and so forth. Some of these can be modified by
the following functions.

set_inf
is used to set the representation of infinity. The default creates the output\infty
but here's how it can be changed.julia> lap(1/0) \infty julia> set_inf("\\text{inf}") # note the double backslash "\\text{inf}" julia> lap(1/0) \text{inf}

set_nan
is used to set the LaTeX for notanumber:julia> lap(0/0) \text{NaN} julia> set_nan("\\text{nan}") "\\text{nan}" julia> lap(0/0) \text{nan}

set_bool
is used to set the LaTeX form oftrue
andfalse
. By default, these output\textrm{T}
and\textrm{F}
. This is how these can be changed:julia> lap(true) \mathrm{T} julia> set_bool("\\textsf{true}", "\\textsf{false}") ("\\textsf{true}","\\textsf{false}") julia> lap(true) \textsf{true}

set_im
changes the symbol used for the imaginary unit. Some folks like j instead of i:julia> z = 3+2im 3 + 2im julia> lap(z) 3+2i julia> set_im("j") "j" julia> lap(z) 3+2j

set_emptyset
is used to specify how an empty set should be rendered.julia> C = Set() Set{Any}({}) julia> lap(C) \emptyset julia> set_emptyset("\\{ \\}") "\\{ \\}" julia> lap(C) \{ \}
Users might like to try
\varnothing
as a nice alternative to\empytset
. In that case, the Julia command would beset_emptyset("\\varnothing")
. 
set_align
is used to specify the alignment character for arrays. By default elements of columns are aligned to their center. Use one ofl
,r
, orc
as the alignment character.julia> lap(A) \left[ \begin{array}{c} 2 \\ 10 \\ 544 \\ \end{array} \right] julia> set_align("r") julia> lap(A) \left[ \begin{array}{r} 2 \\ 10 \\ 544 \\ \end{array} \right]

set_delims
is used to specify the left and right delimiters used for vectors and matrices.julia> A = int(eye(2)) 2x2 Array{Int64,2}: 1 0 0 1 julia> lap(A) \left[ \begin{array}{cc} 1 & 0 \\ 0 & 1 \\ \end{array} \right] julia> set_delims("(", ")") # set delimiters to be open/close parens ("(",")") julia> lap(A) \left( \begin{array}{cc} 1 & 0 \\ 0 & 1 \\ \end{array} \right)
set_nothing
is used to specify the output of anothing
value. For example, to output an emdash, we can do this:julia> lap(nothing) \mathrm{nothing} julia> set_nothing("\\mathrm{}") "\\mathrm{}" julia> lap(nothing) \mathrm{}
Adding new types
There are other Julia types (such as UnitRange
) for which
we have not implemented a conversion to LaTeX. In this
case lap
(and our other functions) simply convert the type
to an String
.
julia> lap(1:10)
1:10
If we want to create a LaTeX representation, then we
need to define a suitable version of latex_form
like this:
julia> import LatexPrint.latex_form
julia> latex_form(x::UnitRange) = "[" * string(x.start) * "," * string(x.stop) * "]"
latex_form (generic function with xxx methods)
julia> lap(1:10)
[1,10]