The three ways to use math mode ($
…$
,
\(
…\)
and
\begin{math}
…\end{math}
) are supported.
The three ways to use display math mode ($$
…$$
,
\[
…\]
and
\begin{displaymath}
… \end{displaymath}
) are also
supported.
Furthermore, \ensuremath
behaves as expected.
The equation
, eqnarray
, eqnarray*
environments
are supported.
Equation labelling and numbering is performed in the first two
environments, using the equation
counter.
Additionally, numbering can be suppressed in one row of an
eqnarray
, using the \nonumber
command.
Math mode is not as powerful in H^{E}V^{E}A as in L^{A}T_{E}X. The
limitations of math mode can often be surpassed by using math display
mode. As a matter of fact, math mode is for intext formulas. From
the html point of view, this means that math mode does not close
the current flow of text and that formulas in math mode must be
rendered using textlevel elements only. By contrast, displayed
formulas can be rendered using blocklevel elements. This means that
H^{E}V^{E}A have much more possibilities in display context than inside
normal flow of text. In particular, stacking text elements one above
the over is possible only in display context.
For instance compare how H^{E}V^{E}A renders
$\frac{1}{\sum_{i=1}^{\infty} i$
as: 1/∑_{i=1}^{∞} i, and
$$\frac{1}{\sum_{i=1}^{\infty} i$$
as:

H^{E}V^{E}A admits, subscript (_
), superscripts (^
) and
fractions (\frac{
numer}{
denom}
).
The best effect is obtained in display mode, where html
table
element is extensively used.
By contrast, when not in display mode, H^{E}V^{E}A uses only
SUB
and SUP
textlevel elements to render superscrits
and subscript, and the result may not be very satisfying.
However,
simple subscripts and superscripts, such as x_i
or x^2
,
are always rendered using the SUB
and SUP
textlevel elements and their appearance should be correct
even in intext formulas.
When occurring outside math mode, characters _
and ^
act as
ordinary characters and get echoed to the output. However, a warning
is issued.
An attempt is made to render all ellipsis constructs (\ldots
,
\cdots
, \vdots
and \ddots
). The effect may be
strange for the latter two.
The n^{th} root command \sqrt
is supported only for n=3,4, thanks to the existence of Unicode characters for the same. For the others, we shift to fractional exponents, in which case, the \sqrt
command is
defined as follows:
\newcommand{\sqrt}[3][2]{\left(#2\right)^{1/#1}}
Then, the source
fragment: $$\sqrt[5]{\frac{1}{n!}} + \sqrt[3]{\pi} + \sqrt{\pi}$$
gets rendered
as follows:
 +  ∛ 
 +  √ 

The support for unicode symbols offered by modern browsers allows to translate almost all math symbols correctly.
Loglike functions and variable sizedsymbols are recognized and their
subscripts and superscripts are put where they should in display mode.
Subscript and superscript placement can be changed using the
\limits
and \nolimits
commands.
Big delimiters are also handled.
The commands \stackrel
, \underline
and \overline
are recognized.
They produce sensible output in display mode.
In text mode, these macros call the \textstackrel
,
\textunderline
and \textoverline
macros.
These macros perform the following default actions
U
textlevel element.
The command \boxed
works well both in display and normal math mode. Input of the form \boxed{\frac{\pi}{2}}
produces π/2 in normal math, and

in displaymath mode. The commands \bigl,\bigr
etc. are also rendered well. Some examples can be found here.
Math accents that have coresponding text accents
(\hat
, \tilde
, etc.) are
handled by default. They in fact act as the
corresponding textmode accents (Section B.3.4).
As a consequence, they work properly only on ascii letters.
This may be quite cumbersome, but at least some warnings draw user’s
attention on the problem.
If accents are critical to your document and that H^{E}V^{E}A issues
a lot of warnings, a solution is to redefine the math accent command.
A suggested replacement is using limit superscripts.
That way accents are positioned above symbols in display mode and
after symbols in text mode.
\renewcommand{\hat}[1]{\mathop{#1}\limits^{\textasciicircum}\nolimits} Displayed: $$ \hat{\mu} = \hat{\Delta}. $$ In text: $\hat{\mu} = \hat{\delta}$
An you get, displayed:
 = 
 . 
In text: µ^{^} = δ^{^}.
Whereas, with the default of \hat
being \^
,
you get “µ = δ”, with the following warnings:
./tmp.tex:4652: Warning: Application of '\^' on '\mu' failed ./tmp.tex:4652: Warning: Application of '\^' on '\delta' failed
The \vec
command is rendered differently in display and nondisplay mode. In
display mode, the arrow appears in normal position, while in
nondisplay the arrow appears as an ordinary superscript.
\vec{u} in text mode: u^{→}, \vec{u} in display mode: 

Most “extensible accents” (\widetilde
, \widehat
, etc.)
are not even defined.
There are a few exceptions: line “accents”:

Brace “accents”:

And arrow “accents”:

By contrast with L^{A}T_{E}X, space in the input matters in math mode.
One or more spaces are translated to one space.
Furthermore,
spaces after commands (such as \alpha
) are echoed
except for invisible commands (such as \tt
).
This allows users to control space in their formulas, output being
near to what can be expected.
Explicit spacing commands (\,
, \!
, \:
and
\;
) are recognized, the first two commands do nothing, while
the others two output one space.
Letters are italicized inside math mode and this cannot be
changed. The appearance of
other symbols can be changed using
L^{A}T_{E}X 2є style changing commands (\mathbf
, etc.).
The commands \boldmath
and \unboldmath
are not
recognized. Whether symbols belonging to the symbol font are affected
by style changes or not is browser dependent.
The \cal
declaration and the \mathcal
command (that
yield calligraphic letters in L^{A}T_{E}X) exist. They yield red letters by
default.
Observe that this does not corresponds directly to how L^{A}T_{E}X manage style in math mode and that, in fact, style cannot really change in math mode.
Math style changing declarations \displaystyle
and
\textstyle
do nothing when H^{E}V^{E}A is already in the requested
mode,
otherwise they issue a warning.
This is so because H^{E}V^{E}A implements displayed maths as tables,
which require to be both opened and closed and introduce line breaks
in the output.
As a consequence, warnings on \displaystyle
are to be taken seriously.
The commands \scriptstyle
and \scriptscriptstyle
perform type size changes.