vv

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6 years, 278 days

MaplePrimes Activity


These are questions asked by vv

The random connected graphs used to be connected in Maple 2020. But then ...

restart;
with(GraphTheory):
with(RandomGraphs):
N:=100: n:=20: m:=30:
add(`if`(IsConnected(RandomGraph(n,m,connected)), 1, 0), 1..N) <> N;

        54 <> 100

It's sad when a bug is found for such a simple problem!

sys := [x*y*z = 0, x*y*z + x*z + z = 0, x*y*z + x*y + x = 0]:
solve(sys, {x,y,z});    # OK
#         {x = 0, y = y, z = 0}, {x = x, y = -1, z = 0}

solve(sys, [x,y,z]);    # ???
#                               []

 

The following example (from help, direct call, without with) does not work.

restart;
(Q[`0`],Q[`1`],Q[`+`],Q[`-`],Q[`*`],Q[`/`],Q[`=`]) := (0,1,`+`,`-`,`*`,`/`,`=`):
A := Matrix([[2,1,4,6],[3,2,1,7],[0,0,5,1],[0,0,3,8]]):
LinearAlgebra:-Generic:-Determinant[Q](A, ':-method' = ':-BerkowitzAlgorithm');

==> error, (in hasoption)

We must use:

LinearAlgebra:-Generic:-Determinant[Q](A, method=LinearAlgebra:-Generic:-BerkowitzAlgorithm); # 37

which I suppose is not intended!
That's because the keyword name in the code appears as 'BerkowitzAlgorithm' instead of ':-BerkowitzAlgorithm'
(The problem occurs because there is an export LinearAlgebra:-Generic:-BerkowitzAlgorithm). 
 

I seem to remember that the save command had a bug about truncating big integers, and it was solved.
But now (Maple 2020) it is present again.
I wonder whether it is present in Maple 2021 too.

restart;
fname:="d:/tmp/ftest.mpl":
f:=proc(n)
  local i,k;
  for i to n do f(i):=parse(cat("", seq(k mod 10, k=1..10*i))) od;
  f(n);
end:

f(80):
length(%);  # 800, ok
save f, fname;
f:='f':
#restart;
read fname:
f(80):
length(%);  # 100  ???

 

Two days ago I have answered a question about using numapprox:-infnorm for functions of several variables. The question is now deleted. Is it possible to find whether it was deleted by the author (even if she/he has used the "best answer" tag)?

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