## 20359 Reputation

16 years, 26 days

## Strange behavior of evalf...

Maple

evalf(10.2^20, 50);

evalf((10+1/5)^20, 50);

Where are 50 digits of the first result?

## Strange behavior of the procedure...

It is well known that  operating in  geometry  package when setting objects symbolically some inconveniences arise. The error occurs if you do not set limits on the parameters. I wrote the procedure for finding center and radius of the circumscribed circle, devoid of drawbacks:

restart;

Circumcircle:=proc(a,b,c)

local x1, y1, x2, y2, x3, y3, n;

uses geometry;

x1,y1:=op(a); x2,y2:=op(b); x3,y3:=op(c);

n:=x2*y3-x3*y2+x3*y1-x1*y3+x1*y2-x2*y1;

point(A,a), point(B,b), point(C,c);

if type(n,realcons) then triangle(T,[A,B,C]); circumcircle(cc,T,'centername'=OO);

triangle(T,[A,B,C]); circumcircle(cc,T,'centername'=OO);

end proc:

At initial startup procedure works correctly:

Circumcircle([x1,y1], [x2,y2], [x3,y3]);

But if you change the arguments of the procedure, an error occurs:

Circumcircle([x1,1], [x2,y2], [x3,y3]);

But if you run the procedure again with the same arguments, the error disappears:

Circumcircle([x1,1], [x2,y2], [x3,y3]);

What is the reason?

Circumcircle.mws

## Bug in testing functions?...

Obviously, that  f:=x->x^3  is the same function as  g:=t->t^3 . But

f:= x-> x^3;  g:= t-> t^3;

is(f=g);

Worse yet

f:= x-> x^3;  g:= x-> x^3;

is(f=g);

## Analog of discont=true in plot3d?...

Is there some sort of analog of  option  discont=true  in  plot3d?  Can I remove these vertical cylindrical surfaces in the following example? They correspond to the zeros of the denominator:

plot3d((x^2+sin(x))/(y^2+cos(x)), x = -7 .. 7, y = -5 .. 5, view = [-7 .. 7, -6 .. 6, -1 .. 7], numpoints = 50000, scaling = constrained, axes = normal);

plots[implicitplot](y^2+cos(x), x = -7 .. 7, y = -5 .. 5, scaling = constrained, numpoints = 5000);

## Unicode characters in textplot...

Maple

Is it possible to use Unicode characters in  textplot  command? In the application that I'm developing, the signs of the chess pieces should be used.

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