vv

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7 years, 70 days

MaplePrimes Activity


These are questions asked by vv

The function

f := sin(x)/sqrt(2+sin(2*x));

has a simple elementary antiderivative but int(f,x) is huge and not elementary. What method would you suggest to find it?

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  ???

 

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