Ask Your Question
1

Bizarre error

asked 10 years ago

foliot gravatar image

updated 10 years ago

FrédéricC gravatar image

I'm sorry that the function in question is rather messy, but the problem is rather specific. I'm setting a constant 'c' and evaluating the local maximum of a function like so:

c = 1E6
find_local_maximum(lambda f: abs(1000*(2*pi*f*i)/(0.1*(2*pi*f*i)^2+1000*(2*pi*f*i)+c)), 1000, 3000)

In this case, I get the expected output. If I set c = 1E7, or a nearby value, like c = 1.123E7 or c = 3E7, I get the following error:

RuntimeError: ECL says: THROW: The catch MACSYMA-QUIT is undefined.

Now, if I set c = 5E7or c = 1E8, I get no error.

It's also worth noting that find_local_minimum with the exact same set of values and function does not have this same issue. Finally, the type of c is sage.rings.real_mpfr.RealLiteral in each case.

What could be causing this problem? Is there a workaround or a potential bug fix?

Preview: (hide)

1 Answer

Sort by » oldest newest most voted
1

answered 10 years ago

vdelecroix gravatar image

Hello,

I got the same problem (using sage-6.4).

At least, here is a workaround using fast_callable (which is also much faster)

sage: expr = abs(1000*(2*pi*f*i)/(0.1*(2*pi*f*i)^2+1000*(2*pi*f*i)+c))
sage: g = fast_callable(expr.subs(c=1E6), domain=CDF, vars=[f])
sage: find_local_maximum(g, 1000, 3000)
(1.0, (1591.549431507781+0j))
sage: g = fast_callable(expr.subs(c=1E7), domain=CDF, vars=[f])
sage: find_local_maximum(g, 1000, 3000)
(1.0, (1591.549431507781+0j))

fast_callable somehow tries to compile your expression in a fast function. If you intend to evaluate a lot an expression it is always a good idea.

One annoying thing is that you need to declare the function to be over complex because you use i in your formula.

Vincnet

Preview: (hide)
link

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Question Tools

1 follower

Stats

Asked: 10 years ago

Seen: 878 times

Last updated: Nov 14 '14