* Re: metafun: error when I call the same function twice consecutively.
[not found] <mailman.1.1527847201.14764.ntg-context@ntg.nl>
@ 2018-06-01 11:29 ` Jeong Dal
2018-06-01 14:24 ` Alan Braslau
0 siblings, 1 reply; 5+ messages in thread
From: Jeong Dal @ 2018-06-01 11:29 UTC (permalink / raw)
To: list ntg-context@ntg.nl ntg-context@ntg.nl ntg-context@ntg.nl
ntg-context@ntg.nl
Dear Henri Menke,
Thank you for the solution.
After inserting a line “save x, y;”, it works.
Thank you so much.
Best regards,
Dalyoung
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: metafun: error when I call the same function twice consecutively.
2018-06-01 11:29 ` metafun: error when I call the same function twice consecutively Jeong Dal
@ 2018-06-01 14:24 ` Alan Braslau
2018-06-02 0:30 ` Jeong Dal
0 siblings, 1 reply; 5+ messages in thread
From: Alan Braslau @ 2018-06-01 14:24 UTC (permalink / raw)
To: Jeong Dal; +Cc: mailing list for ConTeXt users
On Fri, 01 Jun 2018 20:29:41 +0900
Jeong Dal <haksan@me.com> wrote:
> After inserting a line “save x, y;”, it works.
This is also defined as "clearxy ;"
For those learning MetaPost, simplifying, z is defined as "(x,y)" so
one can write
z = (a,b) ;
This is an EQUATION in MetaPost
(x,y) = (a,b) ;
not an assignment (as in most other languages), actually a pair of
equations:
x = a ; y = b ;
When x and y are unknown, this can be "solved". When x and y contain
values, it leads to "inconsistent equations".
One *cannot* write
z =: (a,b) ;
("=:" is the assignment operator),
for z is just a macro, not a "pair" object or variable.
This can be *very* confusing when learning MetaPost.
Alan
P.S.
for i=0 upto n:
z[i] = (i,0) ;
endfor
works as each element of the (pseudo)array z is unknown, at least the
first time that it is used.
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maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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* Re: metafun: error when I call the same function twice consecutively.
2018-06-01 14:24 ` Alan Braslau
@ 2018-06-02 0:30 ` Jeong Dal
0 siblings, 0 replies; 5+ messages in thread
From: Jeong Dal @ 2018-06-02 0:30 UTC (permalink / raw)
To: Alan Braslau,
list ntg-context@ntg.nl ntg-context@ntg.nl ntg-context@ntg.nl
ntg-context@ntg.nl
Dear Alan,
Thank you for the clear explanation about z.
I tought that z is a special variable different from other pairs.
Now, I know that it is an equation.
Thank you again.
Best regards,
Dalyoung
> 2018. 6. 1. 오후 11:24, Alan Braslau <braslau.list@comcast.net> 작성:
>
> On Fri, 01 Jun 2018 20:29:41 +0900
> Jeong Dal <haksan@me.com> wrote:
>
>> After inserting a line “save x, y;”, it works.
>
> This is also defined as "clearxy ;"
>
> For those learning MetaPost, simplifying, z is defined as "(x,y)" so
> one can write
> z = (a,b) ;
> This is an EQUATION in MetaPost
> (x,y) = (a,b) ;
> not an assignment (as in most other languages), actually a pair of
> equations:
> x = a ; y = b ;
> When x and y are unknown, this can be "solved". When x and y contain
> values, it leads to "inconsistent equations".
>
> One *cannot* write
> z =: (a,b) ;
> ("=:" is the assignment operator),
> for z is just a macro, not a "pair" object or variable.
>
> This can be *very* confusing when learning MetaPost.
>
> Alan
>
> P.S.
> for i=0 upto n:
> z[i] = (i,0) ;
> endfor
> works as each element of the (pseudo)array z is unknown, at least the
> first time that it is used.
___________________________________________________________________________________
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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___________________________________________________________________________________
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: metafun: error when I call the same function twice consecutively.
2018-06-01 2:22 ` Jeong Dal
@ 2018-06-01 3:19 ` Henri Menke
0 siblings, 0 replies; 5+ messages in thread
From: Henri Menke @ 2018-06-01 3:19 UTC (permalink / raw)
To: ntg-context
On 01/06/18 14:22, Jeong Dal wrote:
> Hi,
>
> I defined a function using MetaFun, and call it to draw a figure.
> It is OK when I call it once.
> But there is an error when it runs the same function second time.
> (it stops when it call fap(3,2) after fap(2,2))
>
> I have no idea what is wrong and how to fix it.
> Would you please tell me what I miss?
You have to save x, y; otherwise z[i] = ... will be an ill-defined equation.
\startMPpage
numeric u; u := 1cm;
path p[];
def fap(expr n, m) =
begingroup ; save x, y ;
numeric size ; size := m*u ;
for i = 0 upto (n*n-1):
z[i] = ((i mod n),(floor(i/n)))*size;
drawdot z[i] withpen pencircle scaled 5pt withcolor blue;
endfor ;
endgroup ;
enddef;
fap(2,2);
fap(3,2);
\stopMPpage
>
> Thank you.
> Best regards,
>
> Dalyoung
>
> %%%%%%%
> \startbuffer[test]
> numeric u; u := 1cm;
> path p[];
>
> def fap(expr n, m) =
> numeric size; size := m*u;
>
> for i = 0 upto (n*n-1):
> z[i] = ((i mod n),(floor(i/n)))*size;
> drawdot z[i] withpen pencircle scaled 5pt withcolor blue;
> endfor;
> enddef;
>
> fap(2,2);
> fap(3,2);
> \stopbuffer
>
> \starttext
> \processMPbuffer[test]
> \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
> webpage : http://www.pragma-ade.nl / http://context.aanhet.net
> archive : https://bitbucket.org/phg/context-mirror/commits/
> wiki : http://contextgarden.net
> ___________________________________________________________________________________
>
___________________________________________________________________________________
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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___________________________________________________________________________________
^ permalink raw reply [flat|nested] 5+ messages in thread
* metafun: error when I call the same function twice consecutively.
[not found] <mailman.1.1527760801.30763.ntg-context@ntg.nl>
@ 2018-06-01 2:22 ` Jeong Dal
2018-06-01 3:19 ` Henri Menke
0 siblings, 1 reply; 5+ messages in thread
From: Jeong Dal @ 2018-06-01 2:22 UTC (permalink / raw)
To: list ntg-context@ntg.nl ntg-context@ntg.nl ntg-context@ntg.nl
ntg-context@ntg.nl
Hi,
I defined a function using MetaFun, and call it to draw a figure.
It is OK when I call it once.
But there is an error when it runs the same function second time.
(it stops when it call fap(3,2) after fap(2,2))
I have no idea what is wrong and how to fix it.
Would you please tell me what I miss?
Thank you.
Best regards,
Dalyoung
%%%%%%%
\startbuffer[test]
numeric u; u := 1cm;
path p[];
def fap(expr n, m) =
numeric size; size := m*u;
for i = 0 upto (n*n-1):
z[i] = ((i mod n),(floor(i/n)))*size;
drawdot z[i] withpen pencircle scaled 5pt withcolor blue;
endfor;
enddef;
fap(2,2);
fap(3,2);
\stopbuffer
\starttext
\processMPbuffer[test]
\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
webpage : http://www.pragma-ade.nl / http://context.aanhet.net
archive : https://bitbucket.org/phg/context-mirror/commits/
wiki : http://contextgarden.net
___________________________________________________________________________________
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[not found] <mailman.1.1527847201.14764.ntg-context@ntg.nl>
2018-06-01 11:29 ` metafun: error when I call the same function twice consecutively Jeong Dal
2018-06-01 14:24 ` Alan Braslau
2018-06-02 0:30 ` Jeong Dal
[not found] <mailman.1.1527760801.30763.ntg-context@ntg.nl>
2018-06-01 2:22 ` Jeong Dal
2018-06-01 3:19 ` Henri Menke
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