The \frac macro.

The \frac macro.

[John R. Culleton]

Knuth defines a macro for simple fractions such as 3/4 etc. and calls 
it \frac:
\def\frac#1/#2{\leavevmode
\kern.1em \raise .5ex \hbox{\the\scriptfont0 #1}%
\kern-.1em $/$%
\kern -.15em \lower .25ex \hbox{\the\scriptfont0 #2}}%

The call is e.g., \frac 3/4.


This works fine in Context. However if I undefine the Knuth macro and 
still use the same \frac call I don't get an error message but the 
results are quite different.  I get both a stroke and a bar between 
the 3 and the 4. 

Is there another macro in Context called \frac and if so how is it 
called?
-- 
John Culleton
Able Indexing and Typesetting
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Re: The \frac macro.

[Mojca Miklavec]

On 4/22/07, John R. Culleton <john@wexfordpress.com> wrote:
> Knuth defines a macro for simple fractions such as 3/4 etc. and calls
> it \frac:
> \def\frac#1/#2{\leavevmode
> \kern.1em \raise .5ex \hbox{\the\scriptfont0 #1}%
> \kern-.1em $/$%
> \kern -.15em \lower .25ex \hbox{\the\scriptfont0 #2}}%
>
> The call is e.g., \frac 3/4.
>
>
> This works fine in Context. However if I undefine the Knuth macro and
> still use the same \frac call I don't get an error message but the
> results are quite different.  I get both a stroke and a bar between
> the 3 and the 4.

Because what you type is then equal to "\frac{3}{/}4", similar to the
standard command in LaTeX. \frac already exists and accepts two
arguments.

Mojca

Re: The \frac macro.

[Aditya Mahajan]

On Sun, 22 Apr 2007, John R. Culleton wrote:

> Knuth defines a macro for simple fractions such as 3/4 etc. and calls
> it \frac:
> \def\frac#1/#2{\leavevmode
> \kern.1em \raise .5ex \hbox{\the\scriptfont0 #1}%
> \kern-.1em $/$%
> \kern -.15em \lower .25ex \hbox{\the\scriptfont0 #2}}%
>
> The call is e.g., \frac 3/4.
>
>
> This works fine in Context. However if I undefine the Knuth macro and
> still use the same \frac call I don't get an error message but the
> results are quite different.  I get both a stroke and a bar between
> the 3 and the 4.
>
> Is there another macro in Context called \frac and if so how is it
> called?

\frac {a}{b} is equivalent to plain tex's {a \over b}.

There is also a command similar to what you want to define in ConTeXt. 
It is called vulgar fraction. From core-mis.tex

%D \starttabulate
%D \HL
%D \NC \bf method \NC \bf visualization \NC\NR
%D \HL
%D \NC 0 \NC \chardef\vulgarfractionmethod0\vulgarfraction{1}{2} 
\NC\NR
%D \NC 1 \NC \chardef\vulgarfractionmethod1\vulgarfraction{1}{2} 
\NC\NR
%D \NC 2 \NC \chardef\vulgarfractionmethod2\vulgarfraction{1}{2} 
\NC\NR
%D \NC 3 \NC \chardef\vulgarfractionmethod3\vulgarfraction{1}{2} 
\NC\NR
%D \HL
%D \stoptabulate

However, if you plan to use such fractions in serious work, do read 
the introduction of xfrac 
(ftp://tug.ctan.org/pub/tex-archive/macros/latex/exptl/xfrac/doc/xfrac.pdf)
I think that the vigrule vs solidus argument also applies to ConTeXt's 
definition.

Aditya

Re: The \frac macro.

[luigi scarso]

> Is there another macro in Context called \frac and if so how is it
> called?
I use  (e)grep in this situations, it's more texnician.


luigi
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