%+-%                    Plus Minus, it shows x and calculates x +- y
%->%                    Right arrow, presented as x -> y
%.%                     Product x * y, shown as x dot y
%<-%                    Left arrow, presented as x <- y
%<->%                   Double sided arrow, presented as x <-> y
%<=%                    Right double arrow, displayed as x => y
%<=>%                   If and only if condition, displayed as x <=> y
%==%                    Equivalence, shown as x == y
%=>%                    Left double arrow, displayed as x <= y
%=~%                    Congruence, shown as x =~ y
%dbldown%               Down double arrow, displayed as x dArr y
%dblup%                 Up double arrow, displayed as x uArr y
%down%                  Down arrow, presented as x downarrow y
%prop%                  Proportional, shown as x o< y
%up%                    Up arrow, presented as x up y
%~~%                    Approximate equality, shown as x ~~ y
add                     add
add_left                add_left
add_right               add_right
cal                     Calligraphic font
canonical               Canonicalize an R call: Reorder the function
                        arguments
decorations             Identity functions for different decorations
denote                  denote This is a function that allows the user
                        to insert abbreviations in the formula, explain
                        them and make the needed computations
dfrac                   Division displayed as large fraction
dot                     Multiplication
fname                   Return function body
fontstyles              Identity functions for different font styles
frac                    Division displayed as fraction
hook                    Hook for custom symbols
instead                 instead
math                    Adds the class "math" to the object for knitr
                        output via 'mathout()'
mathjax                 Mathjax output
mathml                  MathML output
mathml_preproc          Map R operators to their respective Prolog
                        counterparts
mathout                 MathML or MathJax output, depending on the
                        knitr context
name                    Add a name attribute to an element (most often,
                        an R function)
omit                    omit
omit_left               omit_left This is a function that allows the
                        user to highlight the mistakes, in particular
                        the omissions in the left-hand side of the
                        expression
omit_right              omit_right This is a function that allows the
                        user to highlight the mistakes, in particular
                        the omissions in the right-hand side of the
                        expression
prod_over               product over a range. On the R side, this
                        function just returns the product of the first
                        argument, but allows for decorations.
sum_over                sum over a range. On the R side, this function
                        just returns the first argument, but allows for
                        decorations.
