strange output in math display mode

strange output in math display mode

[Jeong Dal]

Dear Hans,

After updating the minimal, I got a strange output of math display mode.
Would you please check it?

Here is an example.

Best regards,
Thank you.

Dalyoung

%%%%%%%%%%%%
\starttext

Here is a strange output of math formula. It is displayed correctly in text line, but is displayed strangely in math display mode.
\blank
Here is a correct output  in text line.  $\int_0^t B(s)\ dB(s) = \frac{1}{2} B^2(t) - \frac{1}{2} t.$
\blank
But in the output of display mode, the location of the sub- super-script of the integral sign is not normal and the output of \type{ \frac{1}{2} B^2(t)} is wrong.

\startformula
\int_0^t B(s)\ dB(s) = \frac{1}{2} B^2(t) - \frac{1}{2} t.
\stopformula
\stoptext
%%%%%%%%%%%%%%
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Re: strange output in math display mode

[Otared Kavian]

Hi Dalyoung,

I can confirm that in displayed math, the digit 1 in the command \frac{1}{2} results in 
494 > 1
which is unexpected…
However the command {1 \over 2} gives the correct result.

Actually there seems to be a spurious
	494 >
in the source tree of the latest release, since any command such as \frac{a}{2} results in
494 > a

Best regards: OK

> On 21 Dec 2015, at 14:01, Jeong Dal <haksan@me.com> wrote:
> 
> Dear Hans,
> 
> After updating the minimal, I got a strange output of math display mode.
> Would you please check it?
> 
> Here is an example.
> 
> Best regards,
> Thank you.
> 
> Dalyoung
> 
> %%%%%%%%%%%%
> \starttext
> 
> Here is a strange output of math formula. It is displayed correctly in text line, but is displayed strangely in math display mode.
> \blank
> Here is a correct output  in text line.  $\int_0^t B(s)\ dB(s) = \frac{1}{2} B^2(t) - \frac{1}{2} t.$
> \blank
> But in the output of display mode, the location of the sub- super-script of the integral sign is not normal and the output of \type{ \frac{1}{2} B^2(t)} is wrong.
> 
> \startformula
> \int_0^t B(s)\ dB(s) = \frac{1}{2} B^2(t) - \frac{1}{2} t.
> \stopformula
> \stoptext
> %%%%%%%%%%%%%%
> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an entry to the Wiki!
> 
> maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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> ___________________________________________________________________________________

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Re: strange output in math display mode

[Wolfgang Schuster]

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> Otared Kavian <mailto:otared@gmail.com>
> 21. Dezember 2015 um 14:14
> Hi Dalyoung,
>
> I can confirm that in displayed math, the digit 1 in the command 
> \frac{1}{2} results in
> 494 > 1
> which is unexpected…
> However the command {1 \over 2} gives the correct result.
>
> Actually there seems to be a spurious
> 494 >
> in the source tree of the latest release, since any command such as 
> \frac{a}{2} results in
> 494 > a
It's a spurious "\??mathstylecache" in math-ini.mkiv and I sent a fix to 
the dev-list.

Wolfgang

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Re: strange output in math display mode

[Alan BRASLAU]

Wolfgang,

Can you explain to us why it should be preferable for ConTeXt users to
employ \frac12 rather than the native TeX construction {1\over 2}?
I understand that the macro \frac does some additional trickery but the
two constructions should *always* yield identical results (when
keyed-in properly).

Of course, Donald Knuth disagrees with \frac from the point of view
of the aesthetics of the syntax.

Alan



On Mon, 21 Dec 2015 15:17:18 +0100
Wolfgang Schuster <schuster.wolfgang@gmail.com> wrote:

> > However the command {1 \over 2} gives the correct result.
> > 
> It's a spurious "\??mathstylecache" in math-ini.mkiv and I sent a fix
> to the dev-list.
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Re: strange output in math display mode

[Aditya Mahajan]

On Tue, 22 Dec 2015, Alan BRASLAU wrote:

> Wolfgang,
>
> Can you explain to us why it should be preferable for ConTeXt users to
> employ \frac12 rather than the native TeX construction {1\over 2}?
> I understand that the macro \frac does some additional trickery but the
> two constructions should *always* yield identical results (when
> keyed-in properly).

One of the troubles with { .... \over ...} and the like is that TeX does 
not know which "style" to use. This can lead to extra processing when 
using any command defined using \mathpalatte (such as \text, stacked 
arrows, and others).

Consider \text{...}. Basically, we want \text{...} to typeset it's 
argument in a \hbox with textsize equal to the normalsize in normal mode 
and equal to script size when used in a subscript and in scriptsciptsize 
when used in a sub-subscript. Now, in traditional tex, when parsing

    {\text{hello} \over 2}

TeX does not kow what size to use for \text{...} until it encounters the 
\over. So, when parsing \text{hello}, TeX generates all possible sizes and 
then prunes them later on. With nested constructs like

{\text{hello}_{\text{world} \over 2} \over 2}

it can lead to exponential number of branches.

With \frac{\text{hello}}{2}, TeX "knows" what style to use for the 
arguments. So, extra processing is not needed (at least, this is the idea 
in LuaTeX; in PDFTeX, multiple sizes need to be generated). This can lead 
to some slightly faster processing.

Also see http://tex.stackexchange.com/a/1261/ answer from Taco. Contrast 
the definition of \cramped given there from one in the LaTeX mathtools 
package 
(http://ctan.bppro.ca/macros/latex/contrib/mathtools/mathtools.dtx) 
[search from MT_cramped_clap_internal:Nn]

Aditya
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___________________________________________________________________________________

Re: strange output in math display mode

[Alan BRASLAU]

So it it a TeX programming limitation.

The risk of leading to an exponential number of branches is addressed
by Knuth at the beginning of Chapter 17 of the TeXbook (p. 139):
"Mathematicians tend to \quote{overuse} \over when they first begin to
typeset their own work on a system like \TEX." ...

At one point, I went back to using \over rather than \frac as the later
was broken and gave no output. This has since been fixed, but I stayed
with \over as I find primary operators to be much more elegant syntax
than multiple argument macros. It is too bad that luatex does not
employ a better programming solution, as the use of \frac{}{} leads to
ugly mathematical source code.

I guess that I should not worry about it too much since, as Knuth points
out in Chapter 17, overuse of \over, etc. leads to ugly results
anyways, just as well as an overuse of \text in mathematical formulas
(as we physicists tend to abuse) also leads to ugly mathematics.

Alan


On Tue, 22 Dec 2015 17:30:22 -0500
Aditya Mahajan <adityam@umich.edu> wrote:

> On Tue, 22 Dec 2015, Alan BRASLAU wrote:
> 
> > Wolfgang,
> >
> > Can you explain to us why it should be preferable for ConTeXt users
> > to employ \frac12 rather than the native TeX construction {1\over
> > 2}? I understand that the macro \frac does some additional trickery
> > but the two constructions should *always* yield identical results
> > (when keyed-in properly).  
> 
> One of the troubles with { .... \over ...} and the like is that TeX
> does not know which "style" to use. This can lead to extra processing
> when using any command defined using \mathpalatte (such as \text,
> stacked arrows, and others).
> 
> Consider \text{...}. Basically, we want \text{...} to typeset it's 
> argument in a \hbox with textsize equal to the normalsize in normal
> mode and equal to script size when used in a subscript and in
> scriptsciptsize when used in a sub-subscript. Now, in traditional
> tex, when parsing
> 
>     {\text{hello} \over 2}
> 
> TeX does not kow what size to use for \text{...} until it encounters
> the \over. So, when parsing \text{hello}, TeX generates all possible
> sizes and then prunes them later on. With nested constructs like
> 
> {\text{hello}_{\text{world} \over 2} \over 2}
> 
> it can lead to exponential number of branches.
> 
> With \frac{\text{hello}}{2}, TeX "knows" what style to use for the 
> arguments. So, extra processing is not needed (at least, this is the
> idea in LuaTeX; in PDFTeX, multiple sizes need to be generated). This
> can lead to some slightly faster processing.
> 
> Also see http://tex.stackexchange.com/a/1261/ answer from Taco.
> Contrast the definition of \cramped given there from one in the LaTeX
> mathtools package 
> (http://ctan.bppro.ca/macros/latex/contrib/mathtools/mathtools.dtx) 
> [search from MT_cramped_clap_internal:Nn]
> 
> Aditya
> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an
> entry to the Wiki!
> 
> maillist : ntg-context@ntg.nl /
> http://www.ntg.nl/mailman/listinfo/ntg-context webpage  :
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> http://contextgarden.net
> ___________________________________________________________________________________


-- 
Alan Braslau
CEA DSM-IRAMIS-SPEC
CNRS UMR 3680
Orme des Merisiers
91191 Gif-sur-Yvette cedex FRANCE
tel: +33 1 69 08 73 15
fax: +33 1 69 08 87 86
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___________________________________________________________________________________

Re: strange output in math display mode

[Hans Hagen]

On 12/22/2015 11:30 PM, Aditya Mahajan wrote:
> On Tue, 22 Dec 2015, Alan BRASLAU wrote:
>
>> Wolfgang,
>>
>> Can you explain to us why it should be preferable for ConTeXt users to
>> employ \frac12 rather than the native TeX construction {1\over 2}?
>> I understand that the macro \frac does some additional trickery but the
>> two constructions should *always* yield identical results (when
>> keyed-in properly).
>
> One of the troubles with { .... \over ...} and the like is that TeX does
> not know which "style" to use. This can lead to extra processing when
> using any command defined using \mathpalatte (such as \text, stacked
> arrows, and others).
>
> Consider \text{...}. Basically, we want \text{...} to typeset it's
> argument in a \hbox with textsize equal to the normalsize in normal mode
> and equal to script size when used in a subscript and in scriptsciptsize
> when used in a sub-subscript. Now, in traditional tex, when parsing
>
>     {\text{hello} \over 2}
>
> TeX does not kow what size to use for \text{...} until it encounters the
> \over. So, when parsing \text{hello}, TeX generates all possible sizes
> and then prunes them later on. With nested constructs like
>
> {\text{hello}_{\text{world} \over 2} \over 2}
>
> it can lead to exponential number of branches.
>
> With \frac{\text{hello}}{2}, TeX "knows" what style to use for the
> arguments. So, extra processing is not needed (at least, this is the
> idea in LuaTeX; in PDFTeX, multiple sizes need to be generated). This
> can lead to some slightly faster processing.

normally this is not what tex spends most time on although indeed it get 
slow as soon as you do 8 (massive) font switches plus other 
initializations (more a macro package issue then)

> Also see http://tex.stackexchange.com/a/1261/ answer from Taco. Contrast
> the definition of \cramped given there from one in the LaTeX mathtools
> package
> (http://ctan.bppro.ca/macros/latex/contrib/mathtools/mathtools.dtx)
> [search from MT_cramped_clap_internal:Nn]

the \over and \above primitives are kind of special in the sense that 
they force the tex parser to backtrack (in practice it goes into another 
state and reconsiders the previous mathlist (of char) to become part of 
the fraction specification)

in the end there is a math list that gets processed and at that point 
tex will figure out the size (it only calculates once not four times as 
it knows what size it's in then)

as adity mantiones, as soon as one wants control over the size one runs 
into the problem that one has to use some construct that calculates all 
sizes (as then we pass an already typeset stream) so that tex when doing 
the fraction can choose the one it needs; this is referred to as 
"choices": if you want a smaller 1 and 2 in  {1\over2} then you need 
something {\allfour{1}\over\allfour{2}} which then quickly let you make 
a helper which then tends to be called \frac and 1\frac2 is not 
something you can do in macros

you can just use {{foo}\over{bar}} if you prefer (use all those braces 
to make things predictable) but then you cannot easily influence styling

luatex introduces a mechanism to predict the upcoming style so that one 
can act upon it and avoid the four choices but that is normally not a 
user level operation (too much code)

the whole idea of \frac is to provide a way to control styling (smaller 
that normal for instance)

in context the fraction mechanism is quite complex as all permutations 
you can imagine are wanted by (different) users and usage (and you don't 
want to know what people put in fractions)

basically you have

   style-a {style-b {{style-c}\over{style-d}}}

kind of cases and every style influences a nested one (in font size, 
spacing etc) and of course mixed use complicates matters (consistent 
spacing, coloring, etc)


-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
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___________________________________________________________________________________

Re: strange output in math display mode

[Hans Hagen]

On 12/23/2015 3:19 AM, Alan BRASLAU wrote:
> So it it a TeX programming limitation.
>
> The risk of leading to an exponential number of branches is addressed
> by Knuth at the beginning of Chapter 17 of the TeXbook (p. 139):
> "Mathematicians tend to \quote{overuse} \over when they first begin to
> typeset their own work on a system like \TEX." ...
>
> At one point, I went back to using \over rather than \frac as the later
> was broken and gave no output. This has since been fixed, but I stayed
> with \over as I find primary operators to be much more elegant syntax
> than multiple argument macros. It is too bad that luatex does not
> employ a better programming solution, as the use of \frac{}{} leads to
> ugly mathematical source code.

Well, it is not impossible in mkiv do make something 1\alansover2 that 
adjusts itself to some settings (i could probably do it right now) but 
who will use it (apart from you) and who would document it then ..

> I guess that I should not worry about it too much since, as Knuth points
> out in Chapter 17, overuse of \over, etc. leads to ugly results
> anyways, just as well as an overuse of \text in mathematical formulas
> (as we physicists tend to abuse) also leads to ugly mathematics.

Hans

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
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___________________________________________________________________________________

Re: strange output in math display mode

[Wolfgang Schuster]

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> Hans Hagen <mailto:pragma@wxs.nl>
> 23. Dezember 2015 um 10:17
> On 12/23/2015 3:19 AM, Alan BRASLAU wrote:
>> So it it a TeX programming limitation.
>>
>> The risk of leading to an exponential number of branches is addressed
>> by Knuth at the beginning of Chapter 17 of the TeXbook (p. 139):
>> "Mathematicians tend to \quote{overuse} \over when they first begin to
>> typeset their own work on a system like \TEX." ...
>>
>> At one point, I went back to using \over rather than \frac as the later
>> was broken and gave no output. This has since been fixed, but I stayed
>> with \over as I find primary operators to be much more elegant syntax
>> than multiple argument macros. It is too bad that luatex does not
>> employ a better programming solution, as the use of \frac{}{} leads to
>> ugly mathematical source code.
>
> Well, it is not impossible in mkiv do make something 1\alansover2 that 
> adjusts itself to some settings (i could probably do it right now) but 
> who will use it (apart from you) and who would document it then ..
Would this method allow fractions in the second form below with ÷ 
instead of \over?

\starttext

\startformula
     1 = \frac{2}{3} + { 1 ÷ 3 }
\stopformula

\stoptext

Wolfgang

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___________________________________________________________________________________

Re: strange output in math display mode

[Hans Hagen]

On 12/22/2015 8:24 PM, Alan BRASLAU wrote:
> Wolfgang,
>
> Can you explain to us why it should be preferable for ConTeXt users to
> employ \frac12 rather than the native TeX construction {1\over 2}?
> I understand that the macro \frac does some additional trickery but the
> two constructions should *always* yield identical results (when
> keyed-in properly).
>
> Of course, Donald Knuth disagrees with \frac from the point of view
> of the aesthetics of the syntax.

Are you sure he disagrees? For instance \frac {12} {34} is less code 
than { {12} \over {34} } and all over the texbook (and web code) 
shortcuts are used. Afaik his idea of TeX is that users should do what 
they like best.

Hans


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                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
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___________________________________________________________________________________

Re: strange output in math display mode

[Alan BRASLAU]

On Wed, 23 Dec 2015 16:52:22 +0100
Hans Hagen <pragma@wxs.nl> wrote:

> > Of course, Donald Knuth disagrees with \frac from the point of view
> > of the aesthetics of the syntax.  
> 
> Are you sure he disagrees? For instance \frac {12} {34} is less code 
> than { {12} \over {34} } and all over the texbook (and web code) 
> shortcuts are used. Afaik his idea of TeX is that users should do
> what they like best.

The issue, which has been largely discussed elsewhere, is that what
Knuth had in mind is for the source code to be as readable as the
formatted result in some sense. I'm sure, Hans, that you agree with
this philosophy.

{12 \over 34} (no inner grouping should be necessary?) reads as we (or
a mathematician) would think, whereas \frac{12}{34} reads as a computer
programmer might think. This last construct is simply UGLY (maybe
"geeks" might disagree).

A computer program should have an elegant syntax, and the syntax should
not be dictated by the implementation but should be coherent with
itself. This is one of the attractions of lua as a language, for it is
quite elegant. Another choice of ours is MetaPost, which is quite
beautiful (much, much more than pgf/TiKz that it inspired), but perhaps
a bit too subtle and somewhat quirky for many users.

I believe that there is a certain lore around the amsmath/LaTeX
\frac{}{} that is not justified, nor should we really be promoting it.
If there is indeed some penalty in handling the primitives \over, etc.
in luatex, then this should eventually be fixed (but I do not believe,
nor do I know, that there is, in practice).

Alan

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