Multiline equations

From Wiki
Revision as of 15:49, 28 April 2006 by Adityam (talk | contribs) (Added definemathalign)
Jump to navigation Jump to search

< Main Page | Math | Math with newmat | MathML >

Basic Alignment

Two modes of input

  • Latex style
\startformula \startalign
 v &= u + at \\
 h &= ut + \frac12 gt^2 \\
\stopalign \stopformula

Note the \\ in the last line, above.

This appears as follows:

  • Context Style
\startformula \startalign
 \NC v \NC = u + at \NR
 \NC h \NC= ut + \frac12 gt^2 \NR
\stopalign \stopformula

(The examples here will focus on the context style, having two styles can be confusing -- Aditya )

Changing the number of columns

The above equations were aligned at =. Suppose you also want the + to align. Well, this is simple in context, simply specify the number of columns with \startalign

\startformula \startalign[n=3]
 \NC v \NC = u \NC+ at \NR
 \NC h \NC= ut \NC+ \frac12 gt^2 \NR
\stopalign \stopformula

Alignment of each column

If you want more control over the formatting, and want the middle column to be center aligned, you can do that by

\startformula \startalign[n=3,align={right,middle,left}]
 \NC v \NC = u \NC+ at \NR
 \NC h \NC= ut \NC+ \frac12 gt^2 \NR
\stopalign \stopformula

This mechanism allows fancier alignments like

\startformula \startalign[n=4,align={left,right,middle,left}]
 \NC \text{We have} \quad \NC v \NC = u \NC+ at \NR
 \NC \text{and}           \NC h \NC= ut \NC+ \frac12 gt^2 \NR
\stopalign \stopformula

Working with equation numbering

aligned equations can be numbered by placing a tag after \NR

\placeformula \startformula \startalign
 \NC v \NC = u + at \NR[eq:v]
 \NC h \NC = ut + \frac12 gt^2 \NR[eq:h]
\stopalign \stopformula
Equation (\in[eq:v]) tells the final velocity after 
time $t$ and equation (\in[eq:h]) tells the distance 
travelled in time $t$.

Changing the number of columns

Defining new alignment structures

New alignment can be defined using \definemathalignment. For example, to emulate gather environment of amsmath, we can use


\startformula \startgather
 \NC  ax^2 + bx + c = 0 \NR
 \NC \text{roots} = \frac{ -b \pm \sqrt{b^2 - 4ac}}{2a} \NR
\stopgather \stopformula


Context provides a \startmathcases \stopmathcases pair to make it easy get cases.

 f(x) = \startmathcases
   \NC x, \NC if $0 \le x \le \frac12$ \NR
   \NC 1-x ,\NC if $\frac12 \le x \le 1$ \NR


The cases environment consists of two columns, separated by \NC. The second column is by default in text mode. Each line must end with a \NR.

Numbered Cases