\triangledown placed too low in Palatino

\triangledown placed too low in Palatino

[Sanjoy Mahajan]

I just noticed that the gradient operator (\triangledown) ends up too
low when using Palatino:

\setupbodyfont[palatino]
\starttext
$\triangledown T$
\stoptext

It seems about 3pt too low.  Without the \setupbodyfont[palatino], the
placement is fine.

(tested with 2013.05.28 and 2014.03.27 betas)

-Sanjoy
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Re: \triangledown placed too low in Palatino

[Jannik Voges]

I think you are using the wrong symbol. Or at least I would prefer \nabla as gradient operator.


Jannik


Am 10.04.2014 um 23:49 schrieb Sanjoy Mahajan <sanjoy@MIT.EDU>:

> I just noticed that the gradient operator (\triangledown) ends up too
> low when using Palatino:
> 
> \setupbodyfont[palatino]
> \starttext
> $\triangledown T$
> \stoptext
> 
> It seems about 3pt too low.  Without the \setupbodyfont[palatino], the
> placement is fine.
> 
> (tested with 2013.05.28 and 2014.03.27 betas)
> 
> -Sanjoy
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> If your question is of interest to others as well, please add an entry to the Wiki!
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Re: \triangledown placed too low in Palatino

[Sanjoy Mahajan]

Jannik,

You are right.  \nabla looks much nicer and is placed correctly.  (I
still think the \triangledown placement is slightly off.)

My environment files from MkII days have \def\nabla{\triangledown}, so I
never tried the true \nabla until your suggestion.

Thank you.

-Sanjoy

Jannik Voges <researchjavo@icloud.com> writes:

> I think you are using the wrong symbol. Or at least I would prefer
> \nabla as gradient operator.
>
>
> Jannik
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Re: \triangledown placed too low in Palatino

[Aditya Mahajan]

On Thu, 10 Apr 2014, Sanjoy Mahajan wrote:

> Jannik,
>
> You are right.  \nabla looks much nicer and is placed correctly.  (I
> still think the \triangledown placement is slightly off.)
>
> My environment files from MkII days have \def\nabla{\triangledown}, so I
> never tried the true \nabla until your suggestion.

In MkIV: \triangledown is mapped to 0x25BD while nabla is mapped to 
0x2207. These are different glyphs.

IIUC, the difference in placement is because \triangledown is defined as a 
mathop (and hence centered on the math-axis) while \nabla is defined as a 
mathord. Compare:

\startformula
   \nabla T
   \quad
   \triangledown T
   \quad
   \mathop{\nabla} T
\stopformula

From what I remember, I was the one who added the mappings for 
triangledown as a mathop based on, I believe, unicode-math package in 
LaTeX. I don't understand what all the "triangle operators" are supposed 
to do. As such, I cannot say whether the wrong placement is due to the 
wrong font metrics or the wrong mapping (mathop vs mathord) by ConTeXt.

Aditya
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Re: \triangledown placed too low in Palatino

[Sanjoy Mahajan]

> I cannot say whether the wrong placement is due to the wrong font
> metrics or the wrong mapping (mathop vs mathord) by ConTeXt.

I tried '\triangle T' (often used as the Laplacian operator, instead of
writing it out as \nabla^2).  That one comes out fine, even though
\triangledown does not.  But they seem to have similar kinds of
defintions/mappings:

From luatex-math.tex :

\def\triangle                  {\Umathchar  "0"0"0025B3 }
\def\triangledown              {\Umathchar  "2"0"0025BD }

So it must be a wrong font metric?

-Sanjoy
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Re: \triangledown placed too low in Palatino

[Aditya Mahajan]

On Fri, 11 Apr 2014, Sanjoy Mahajan wrote:

>> I cannot say whether the wrong placement is due to the wrong font
>> metrics or the wrong mapping (mathop vs mathord) by ConTeXt.
>
> I tried '\triangle T' (often used as the Laplacian operator, instead of
> writing it out as \nabla^2).  That one comes out fine, even though
> \triangledown does not.  But they seem to have similar kinds of
> defintions/mappings:
>
> From luatex-math.tex :
>
> \def\triangle                  {\Umathchar  "0"0"0025B3 }
> \def\triangledown              {\Umathchar  "2"0"0025BD }
>
> So it must be a wrong font metric?

AFAIU, ConTeXt does not use luatex-math.tex. The mappings are defined in 
char-def.lua.

triangle is defined as a mathord (like nabla) while bigtriangleup is a 
mathop (like triangledown).

Aditya
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Re: \triangledown placed too low in Palatino

[Aditya Mahajan]

On Fri, 11 Apr 2014, Aditya Mahajan wrote:

> On Fri, 11 Apr 2014, Sanjoy Mahajan wrote:
>
>>> I cannot say whether the wrong placement is due to the wrong font
>>> metrics or the wrong mapping (mathop vs mathord) by ConTeXt.
>> 
>> I tried '\triangle T' (often used as the Laplacian operator, instead of
>> writing it out as \nabla^2).  That one comes out fine, even though
>> \triangledown does not.  But they seem to have similar kinds of
>> defintions/mappings:
>> 
>> From luatex-math.tex :
>> 
>> \def\triangle                  {\Umathchar  "0"0"0025B3 }
>> \def\triangledown              {\Umathchar  "2"0"0025BD }
>> 
>> So it must be a wrong font metric?
>
> AFAIU, ConTeXt does not use luatex-math.tex. The mappings are defined in 
> char-def.lua.
>
> triangle is defined as a mathord (like nabla) while bigtriangleup is a mathop 
> (like triangledown).

Sorry, bigtriangleup is a mathbin. (As I said, I don't understand how the 
mathclass of different triangle operators is determined).

Aditya
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Re: \triangledown placed too low in Palatino

[Mikael P. Sundqvist]

Instead of \triangle you "should" use \Delta for the laplacian (as you
should use \nabla for the gradient).

Mikael

On Fri, Apr 11, 2014 at 6:06 AM, Sanjoy Mahajan <sanjoy@mit.edu> wrote:
>> I cannot say whether the wrong placement is due to the wrong font
>> metrics or the wrong mapping (mathop vs mathord) by ConTeXt.
>
> I tried '\triangle T' (often used as the Laplacian operator, instead of
> writing it out as \nabla^2).  That one comes out fine, even though
> \triangledown does not.  But they seem to have similar kinds of
> defintions/mappings:
>
> From luatex-math.tex :
>
> \def\triangle                  {\Umathchar  "0"0"0025B3 }
> \def\triangledown              {\Umathchar  "2"0"0025BD }
>
> So it must be a wrong font metric?
>
> -Sanjoy
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Re: \triangledown placed too low in Palatino

[Otared Kavian]

Hi,

The \triangle operator is used for instance in the « symmetric difference » of two subsets: if $E$ is a set and $A \subset E$, and $B \susbet E$, then one defines
\startformula
A \triangle B := (A \cup B) \setminus (A \cap B).
\stopformula
Then the mapping $(A,B) \mapsto A \triangle B$ is a commutative, associative binary operator on the subsets of $E$.

Some people use instead $A \Delta B$, but this is not the traditional, nor the correct way, to write this « symmetric difference » of two sets. This is why, I guess, in TeX \triangle is an operator.
I have seen also \triangledown as an operator, but I don’t recall the context in which it was used…

Regarding the notation \nabla to denote the gradient, and \Delta, to denote the Laplace operator (which by the way can be defined as $\Delta u := \nabla \cdot (\nabla u)$), Mikael Sundqvist gave the correct observations.

Best regards: OK

On 11 avr. 2014, at 05:48, Aditya Mahajan <adityam@umich.edu> wrote:

> On Thu, 10 Apr 2014, Sanjoy Mahajan wrote:
> 
>> Jannik,
>> 
>> You are right.  \nabla looks much nicer and is placed correctly.  (I
>> still think the \triangledown placement is slightly off.)
>> 
>> My environment files from MkII days have \def\nabla{\triangledown}, so I
>> never tried the true \nabla until your suggestion.
> 
> In MkIV: \triangledown is mapped to 0x25BD while nabla is mapped to 0x2207. These are different glyphs.
> 
> IIUC, the difference in placement is because \triangledown is defined as a mathop (and hence centered on the math-axis) while \nabla is defined as a mathord. Compare:
> 
> \startformula
>  \nabla T
>  \quad
>  \triangledown T
>  \quad
>  \mathop{\nabla} T
> \stopformula
> 
> From what I remember, I was the one who added the mappings for triangledown as a mathop based on, I believe, unicode-math package in LaTeX. I don't understand what all the "triangle operators" are supposed to do. As such, I cannot say whether the wrong placement is due to the wrong font metrics or the wrong mapping (mathop vs mathord) by ConTeXt.
> 
> 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
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Re: \triangledown placed too low in Palatino

[Sanjoy Mahajan]

Otared Kavian <otared@gmail.com> writes:

> The \triangle operator is used for instance in the « symmetric
> difference » of two subsets

Ah, good to learn something about pure mathematics.  In my mathematics
degree, my tutor said, "You are very good at the applied material,"
which was not meant as a compliment.

So \triangle should be a \mathop rather than a \mathord?  Right now, as
Aditya pointed out, it's a \mathord ("ordinary"), in contrast to
\bigtriangleup, which is the same character but typeset as a binary
operator ("binary"). From char-def.lua :

 [0x25B3]={
  adobename="whiteuppointingtriangle",
  category="so",
  cjkwd="a",
  description="WHITE UP-POINTING TRIANGLE",
  direction="on",
  linebreak="ai",
  mathspec={
   {
    class="ordinary",
    name="triangle",
   },
   {
    class="binary",
    name="bigtriangleup",
   },
  },
  unicodeslot=0x25B3,
 },

-Sanjoy
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Re: \triangledown placed too low in Palatino

[Hans Hagen]

On 4/13/2014 4:44 AM, Sanjoy Mahajan wrote:
> Otared Kavian <otared@gmail.com> writes:
>
>> The \triangle operator is used for instance in the « symmetric
>> difference » of two subsets
>
> Ah, good to learn something about pure mathematics.  In my mathematics
> degree, my tutor said, "You are very good at the applied material,"
> which was not meant as a compliment.
>
> So \triangle should be a \mathop rather than a \mathord?  Right now, as
> Aditya pointed out, it's a \mathord ("ordinary"), in contrast to
> \bigtriangleup, which is the same character but typeset as a binary
> operator ("binary"). From char-def.lua :
>
>   [0x25B3]={
>    adobename="whiteuppointingtriangle",
>    category="so",
>    cjkwd="a",
>    description="WHITE UP-POINTING TRIANGLE",
>    direction="on",
>    linebreak="ai",
>    mathspec={
>     {
>      class="ordinary",
>      name="triangle",
>     },
>     {
>      class="binary",
>      name="bigtriangleup",
>     },
>    },
>    unicodeslot=0x25B3,
>   },

I can change things but will only do that when all you mathematicians 
have some agreement about it ...

Btw, it is still on my agenda to provide a mechanism for switching 
between math dictionaries (i.e. group symbols in group swith i fneeded 
different properties) so that one can switch between logic, statistics, 
streetfighting or whatever math.

Hans

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Re: \triangledown placed too low in Palatino

[Sanjoy Mahajan]

> I can change things but will only do that when all you mathematicians 
> have some agreement about it ...

Otared points out that the distinction between \triangle and
\bigtriangleup comes from plain TeX.  plain.tex has these definitions:

\mathchardef\triangle="0234
\mathchardef\bigtriangleup="2234

So \triangle is a math ord and \bigtriangleup a math bin.

For compatibility, that should probably stay true in ConTeXt too---even
the low placement of \bigtriangledown, which I don't understand but
which does reproduce plain TeX's placement.

> Btw, it is still on my agenda to provide a mechanism for switching
> between math dictionaries (i.e. group symbols in group switch if needed
> different properties) so that one can switch between logic,
> statistics, streetfighting or whatever math.

Hm, like different dialects of a language.  Plain TeX definitely speaks
a pure-mathematician dialect.  It would be interesting to see what
symbol groups are useful in other dialects.

-Sanjoy
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Re: \triangledown placed too low in Palatino

[Hans Hagen]

On 4/14/2014 11:30 AM, Sanjoy Mahajan wrote:
>> I can change things but will only do that when all you mathematicians
>> have some agreement about it ...
>
> Otared points out that the distinction between \triangle and
> \bigtriangleup comes from plain TeX.  plain.tex has these definitions:
>
> \mathchardef\triangle="0234
> \mathchardef\bigtriangleup="2234
>
> So \triangle is a math ord and \bigtriangleup a math bin.
>
> For compatibility, that should probably stay true in ConTeXt too---even
> the low placement of \bigtriangledown, which I don't understand but
> which does reproduce plain TeX's placement.

why? if compatibility means 'not useable' we should fix it

>> Btw, it is still on my agenda to provide a mechanism for switching
>> between math dictionaries (i.e. group symbols in group switch if needed
>> different properties) so that one can switch between logic,
>> statistics, streetfighting or whatever math.
>
> Hm, like different dialects of a language.  Plain TeX definitely speaks
> a pure-mathematician dialect.  It would be interesting to see what
> symbol groups are useful in other dialects.

http://www.openmath.org/cdindex.html

it would be interesting to come up with a reasonable list of math languages

Hans

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Re: \triangledown placed too low in Palatino

[Sanjoy Mahajan]

Hans Hagen <pragma@wxs.nl> writes:

>> So \triangle is a math ord and \bigtriangleup a math bin.
>>
>> For compatibility, that should probably stay true in ConTeXt too---even
>> the low placement of \bigtriangledown, which I don't understand but
>> which does reproduce plain TeX's placement.
>
> why? if compatibility means 'not useable' we should fix it

Thus, a question for the purer mathematicians on the list: Are there
uses for the lower placement of \bigtriangledown?  As a physicists, I
have used that shape only for the gradient operator (for which one has
\nabla).  But maybe it is used in, say, category theory with a lower
placement?

-Sanjoy
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remove full stop after a title ending with punctuation

[Peng Zhang]

Dear List,

If an article is "How about this?", in the bib list, it will be printed like

author1, author2, ..., How about this?. Journal name...

I am trying to remove "." after "?"

 From reading documents, I think I should change (bibl-apa)
\insertarttitle{\bgroup }{\egroup. }{}%

Right now it will add "." in all cases. Is it possible that I can change 
it to conditional statement.

Something like if the original title ends with punctuation, do nothing, 
otherwise, add ".".

Hope that I made myself clear.

Thank you!

Best,
Peng
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