precise mechanism

Alejandro Jakubi — Thu, 25 Aug 2011 10:55:30 Z

I think that the mechanism, or part of it, can be seen in a procedure named plot/adaptive/evalpoint and created on the fly. Its relevant control part seems to be here:

> stopat(`plot/sample`,10): 
> plot(x+4*sin(x)+(exp(1/x^5)+2.13)*I*1e-7,x=-8..8,
>      thickness=3,color=black);
-8
`plot/sample`:
  10*      x := left+(i-1+jitter[jpos])*gap;

> showstat(`plot/adaptive/evalpoint`,13..19)  

`plot/adaptive/evalpoint` := proc(_x, `plot/_v`)
local err, useevalhf, valid;
       ...
  13   if valid and (true and (type(`plot/_v`[1],('embedded_real')('finite')) 
or type(`plot/_v`[1],('complex')('numeric')) 
and abs(Im(`plot/_v`[1])) < abs(Re(`plot/_v`[1]))*10^(isqrt(Digits)-Digits)) 
and (type(`plot/_v`[2],('embedded_real')('finite')) 
or type(`plot/_v`[2],('complex')('numeric')) 
and abs(Im(`plot/_v`[2])) < abs(Re(`plot/_v`[2]))*10^(isqrt(Digits)-Digits)) 
or not true and type(`plot/_v`[1],('embedded_real')('finite')) 
and type(`plot/_v`[2],('embedded_real')('finite'))) then
  14     `plot/_v`[1] := Re(`plot/_v`[1]);
  15     `plot/_v`[2] := Re(`plot/_v`[2]);
  16     `plot/_v`[3] := Re(`plot/_v`[3])
       else
  17     `plot/_v`[1] := undefined;
  18     `plot/_v`[2] := undefined;
  19     `plot/_v`[3] := undefined
       end if
end proc

thanks

acer — Thu, 25 Aug 2011 16:23:11 Z

Thank you, Alejandro.

I hadn't searched for it as I feared it might non-centralized. But if that is the formula, then that would be a useful clarifying detail for the plot,computation help page.

acer

MaplePrimes - answers and comments on Question, threshold for ignoring nonreal part in plots

precise mechanism

thanks