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< [[Main Page]] | [[Math with newmat]] | [[MathML]] | [[Math_structures]]>

== Introduction ==

TeX was designed for ease of typesetting books that contained mathematics. As ConTeXt is built on top of TeX, it inherits all those features. In addition to these, ConTeXt adds lot of macros to make the typesetting of mathematics easier.

For typesetting of mathematics follows different rules than that of normal text, TeX uses something called "math mode" where some characters get a different meaning to enable a simple syntax for complicated formulas.

==Simple Math==

Typesetting mathematics can be divided into two parts, '''inline''' math (mathematical formulas set within ordinary paragraphs as part of the text) and '''display''' math mathematics set on lines by themselves, often with equation numbers). Inline math consists of maths that is typed in a sentence. For example

<context>
\setuplayout[scale=0.8,width=13cm]
Pythagoras formula, stating \mathematics{a^2 + b^2 = c^2} was one of the first trignometric results
</context>

There are two ways of typing inline math. The TeX way is to surround what you want to type within <code>$</code>...<code>$</code>. Thus, the above will be typed as
<texcode>
Pythagoras formula, stating $a^2 + b^2 = c^2$ was one of the first trignometric results
</texcode>

ConTeXt also provides an alternative way of typing the same result. Instead of dollars, you can write the material for maths inside <cmd>mathematics</cmd>. Thus, an alternate way to type the above is,
<texcode>
Pythagoras formula, stating \mathematics{a^2 + b^2 = c^2} was one of the first trignometric results
</texcode>

Choose the method that suits your style.
((I do not know if there are pros and cons of $..$ vs \mathematics{}. If someone knows, then please elaborate -- aditya ))

Display math is enclosed in a <cmd>startformula</cmd> / <cmd>stopformula</cmd> pair. Thus

<table width="100%" cols="2"><tr valign="top"><td width="50%">
<texcode>
The famous result (once more) is given by
\startformula
c^2 = a^2 + b^2.
\stopformula
</texcode>
</td><td>
This, when typeset, produces the following:

<context>
\setuplayout[scale=0.8,width=13cm]
The famous result (once more) is given by
\startformula
c^2 = a^2 + b^2.
\stopformula
</context>
</td></tr></table>

== Numbering Formulae ==

ConTeXt provides an easy way to number the display maths equations. Simply, put <cmd>placeformula</cmd> before <cmd>startformula</cmd> / <cmd>stopformula</cmd> pair and you will get numbered equations. Thus,
<table width="100%" cols="2"><tr valign="top"><td width="50%">
<texcode>
The famous result (once more) is given by
\placeformula
\startformula
c^2 = a^2 + b^2.
\stopformula
</texcode>
</td><td>
This, when typeset, produces the following:

<context>
\setuplayout[scale=0.8,width=13cm]
The famous result (once more) is given by
\placeformula
\startformula
c^2 = a^2 + b^2.
\stopformula
</context>
</td></tr></table>

The <cmd>placeformula</cmd> command is optional, and produces the equation number; leaving it off produces an unnumbered equation.

== Not so Simple Maths ==

ConTeXt's base mathematics support is built on the mathematics support in plain TeX, thus allowing quite complicated formulas. (There are also some additional macros, such as the <cmd>text</cmd> command for text-mode notes within math.) For instance:
<texcode>
A more complicated equation:
\placeformula
\startformula
{{\theta_{\text{\CONTEXT}}}^2 \over x+2}
= \pmatrix{a_{11}&a_{12}&\ldots&a_{1n}\cr
a_{21}&a_{22}&\ldots&a_{2n}\cr
\vdots&\vdots&\ddots&\vdots\cr
a_{n1}&a_{n2}&\ldots&a_{nn}\cr}
\pmatrix{b_1 \cr b_2 \cr \vdots \cr b_n}
+ \sum_{j=1}^\infty z^j
\left( \sum_{\scriptstyle n=1 \atop \scriptstyle n \ne j}^\infty Z_j^n \right)
\stopformula
</texcode>

which produces

<context>
\setuplayout[scale=0.8,width=13cm]
A more complicated equation:
\placeformula
\startformula
{{\theta_{\text{\CONTEXT}}}^2 \over x+2}
= \pmatrix{a_{11}&a_{12}&\ldots&a_{1n}\cr
a_{21}&a_{22}&\ldots&a_{2n}\cr
\vdots&\vdots&\ddots&\vdots\cr
a_{n1}&a_{n2}&\ldots&a_{nn}\cr}
\pmatrix{b_1 \cr b_2 \cr \vdots \cr b_n}
+ \sum_{j=1}^\infty z^j
\left( \sum_{\scriptstyle n=1 \atop \scriptstyle n \ne j}^\infty Z_j^n \right)
\stopformula
</context>

Context provides a wrapper around tex <cmd>pmatrix</cmd>. The above can be typeset in a contextish way as
<texcode>
A more complicated equation:
\definemathmatrix[pmatrix][left={\left(\,},right={\,\right)}]
\placeformula
\startformula
{{\theta_{\text{\CONTEXT}}}^2 \over x+2}
= \startpmatrix
\NC a_{11} \NC a_{12} \NC \ldots \NC a_{1n} \NR
\NC a_{21} \NC a_{22} \NC \ldots \NC a_{2n} \NR
\NC \vdots \NC \vdots \NC \ddots \NC \vdots \NR
\NC a_{n1} \NC a_{n2} \NC \ldots \NC a_{nn} \NR
\stoppmatrix
\startpmatrix b_1 \NR b_2 \NR \vdots \NR b_n \NR \stoppmatrix
+ \sum_{j=1}^\infty z^j
\left( \sum_{\scriptstyle n = 1 \atop \scriptstyle n \ne j}^\infty Z_j^n \right)
\stopformula
</texcode>
<context>
\setuplayout[scale=0.8,width=13cm]
A more complicated equation:
\definemathmatrix[pmatrix][left={\left(\,},right={\,\right)}]
\placeformula
\startformula
{{\theta_{\text{\CONTEXT}}}^2 \over x+2}
= \startpmatrix
\NC a_{11} \NC a_{12} \NC \ldots \NC a_{1n} \NR
\NC a_{21} \NC a_{22} \NC \ldots \NC a_{2n} \NR
\NC \vdots \NC \vdots \NC \ddots \NC \vdots \NR
\NC a_{n1} \NC a_{n2} \NC \ldots \NC a_{nn} \NR
\stoppmatrix
\startpmatrix b_1 \NR b_2 \NR \vdots \NR b_n \NR \stoppmatrix
+ \sum_{j=1}^\infty z^j
\left( \sum_{\scriptstyle n = 1 \atop \scriptstyle n \ne j}^\infty Z_j^n \right)
\stopformula
</context>

[http://www.pragma-ade.com/texmath.html Here] you can try it "live" (you must go to [http://www.pragma-ade.com/exalogin login] first).

[[MathAlignment]] is covered on a separate page.

==Sub-Formula Numbering==

As mentioned above, formulas can be numbered using the <cmd>placeformula</cmd> command. This (and the related <cmd>placesubformula</cmd> command have an optional argument which can be used to produce sub-formula numbering. For example:

<table width="100%" cols="2"><tr valign="top"><td width="50%">
<texcode>
Examples:
\placeformula{a}
\startformula
c^2 = a^2 + b^2
\stopformula

\placesubformula{b}
\startformula
c^2 = a^2 + b^2
\stopformula
</texcode>
</td><td>
<context>
\setuplayout[scale=0.8,width=8cm]
Examples:
\placeformula{a}
\startformula
c^2 = a^2 + b^2
\stopformula

\placesubformula{b}
\startformula
c^2 = a^2 + b^2
\stopformula
</context>
</td></tr></table>

What's going on here is simpler than it might appear at first glance. Both <cmd>placeformula</cmd> and <cmd>placesubformula</cmd> produce equation numbers with the optional tag added at the end; the sole difference is that the former increments the equation number first, while the latter does not (and thus can be used for the second and subsequent formulas that use the same formula number but presumably have different tags).

This is sufficient for cases where the standard ConTeXt equation numbers suffice, and where only one equation number is needed per formula. However, there are many cases where this is insufficient, and <cmd>placeformula</cmd> defines <cmd>formulanumber</cmd> and <cmd>subformulanumber</cmd> commands, which provide hooks to allow the use of ConTeXt-managed formula numbers with plain TeX equation numbering. These, when used within a formula, simply return the formula number in properly formatted form, as can be seen in this simple example with plain TeX's <cmd>eqno</cmd>. Note that the optional tag is inherited from <cmd>placeformula</cmd>.

<table width="100%" cols="2"><tr valign="top"><td width="50%">
<texcode>
More examples:
\placeformula{c}
\startformula
\let\doplaceformulanumber\empty
c^2 = a^2 + b^2 \eqno{\formulanumber}
\stopformula
</texcode>
</td><td>
<context>
\setuplayout[scale=0.8,width=8cm]
More examples:
\placeformula{c}
\startformula
\let\doplaceformulanumber\empty
c^2 = a^2 + b^2 \eqno{\formulanumber}
\stopformula
</context>
</td></tr></table>

In order for this to work properly, we need to turn off ConTeXt's automatic formula number placement; thus the <cmd>let</cmd> command to empty <cmd>doplaceformulanumber</cmd>, which must be placed <em>after</em> the start of the formula. In many practical examples, however, this is not necessary; ConTeXt redefines <cmd>displaylines</cmd> and <cmd>eqalignno</cmd> to do this automatically.

For more control over sub-formula numbering, <cmd>formulanumber</cmd> and <cmd>subformulanumber</cmd> have an optional argument parallel to that of <cmd>placeformula</cmd>, as demonstrated in this use of plain TeX's <cmd>eqalignno</cmd>, which places multiple equation numbers within one formula.

<table width="100%" cols="2"><tr valign="top"><td width="50%">
<texcode>
Yet more examples:
\placeformula
\startformula
\eqalignno{c^2 &= a^2 + b^2 &\formulanumber{a} \cr
a^2 + b^2 &= c^2 &\subformulanumber{b} \cr
d^2 &= e^2 &\formulanumber\cr}
\stopformula
</texcode>
</td><td>
<context>
\setuplayout[scale=0.8,width=8cm]
Yet more examples:
\placeformula
\startformula
\eqalignno{c^2 &= a^2 + b^2 &\formulanumber{a} \cr
a^2 + b^2 &= c^2 &\subformulanumber{b} \cr
d^2 &= e^2 &\formulanumber\cr}
\stopformula
</context>
</td></tr></table>

Note that both <cmd>formulanumber</cmd> and <cmd>subformulanumber</cmd> can be used within the same formula, and the formula number is incremented as expected. Also, if an optional argument is specified in both <cmd>placefigure</cmd> and <cmd>formulanumber</cmd>, the latter takes precedence.

<table width="100%" cols="2"><tr valign="top"><td width="50%">
<texcode>
More examples for left-located equation number:
\setupformulas[location=left]
\placeformula{d}
\startformula
\let\doplaceformulanumber\empty
c^2 = a^2 + b^2 \leqno{\formulanumber}
\stopformula
and
\placeformula
\startformula
\leqalignno{c^2 &= a^2 + b^2 &\formulanumber{a} \cr
a^2 + b^2 &= c^2 &\subformulanumber{b} \cr
d^2 &= e^2 &\formulanumber\cr}
\stopformula
</texcode>
</td><td>
<context>
\setuplayout[scale=0.8,width=8cm]
More examples for left-located equation no.:
\setupformulas[location=left]
\placeformula{d}
\startformula
\let\doplaceformulanumber\empty
c^2 = a^2 + b^2 \leqno{\formulanumber}
\stopformula
and
\placeformula
\startformula
\leqalignno{c^2 &= a^2 + b^2 &\formulanumber{a} \cr
a^2 + b^2 &= c^2 &\subformulanumber{b} \cr
d^2 &= e^2 &\formulanumber\cr}
\stopformula
</context>
</td></tr></table>

-- 23:46, 15 Aug 2005 (CEST) Prinse Wang

== Other Methods ==
* There are two different math modules on [http://dante.ctan.org/tex-archive/macros/context/contrib/maths/ CTAN], [[Math with nath|nath]] and [[Math with amsl|amsl]]. And there's a [[Math with newmat|new math]] module in the distribution.
* Context now has inbuilt support for [[Math_structures]]
* It is also possible to use most [[LaTeX Math in ConTeXt|LaTeX equations in ConTeXt]] with a relatively small set of supporting definitions.
* The "native" ConTeXt way of math is [[MathML]], an application of [[XML]] - rather verbose but mighty.

==Number Formatting==
There's a special command, <cmd>digits</cmd>, and a own manual about formatting numbers, see [http://www.pragma-ade.com/general/magazines/mag-0003.pdf Pasting digits together]

==Math [[Fonts]]==
* [[Bold Math]]
* [http://homepage.mac.com/atl/tex/EulerContext.pdf Euler in ConTeXt (using Euler math font)] by Adam Lindsay

==Science==
* Esp. for physics there’s the [[units]] module.
* Additions to [[MathML]] are PhysML and ChemML.
* [[Chemistry]]
* There's a module for chemical structure formulae: [[Chemistry|PPCHTeX]] (works also with LaTeX).

[[Category:Math]]

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