PARI's commands

[CRGreathouse]

Originally Posted by science_man_88

well it will return 1 for aredisjoint([],[]) it would also do that if only one is empty as we know the empty set is not disjoint from any set.

What's the problem?

[science_man_88]

Originally Posted by CRGreathouse

What's the problem?

if we take away the if statement on the outside then it tries to find the first element of a 0 element set since that's impossible it would skip to the end and return 1 regardless if they are the same or the fact that [] is a subset of every set.

[CRGreathouse]

Originally Posted by science_man_88

if we take away the if statement on the outside then it tries to find the first element of a 0 element set

No it doesn't. How many times does for(i=1,#A, ...) execute?

[science_man_88]

Originally Posted by CRGreathouse

No it doesn't. How many times does for(i=1,#A, ...) execute?

that doesn't matter because the check I have inside checks with indexes if it's not an index it won't be checked which means if i take away the if it can only return 1.

[axn]

Originally Posted by science_man_88

if we take away the if statement on the outside then it tries to find the first element of a 0 element set since that's impossible it would skip to the end and return 1 regardless if they are the same or the fact that [] is a subset of every set.

So? If one or both of the sets are empty, they _are_ disjoint. Disjoint means "no common element". If one of them is empty, how can there be a common element?

[science_man_88]

Originally Posted by axn

So? If one or both of the sets are empty, they _are_ disjoint. Disjoint means "no common element". If one of them is empty, how can there be a common element?

I was told the empty is part of every set unless that's false [],[] can only return 0 because they have something in common [],set or set,[] have the same reason to return 0 but my code can't work with 0 elements unless I have that outer statement if the statement isn't there it returns 1 (true) that all these are disjoint but everything I've been told makes that a bad result.

[axn]

Originally Posted by science_man_88

I was told the empty is part of every set

Empty set is a _subset_ of every set. It is not an _element_ of every set. "Part of" is not a mathematically meaningful term.

Originally Posted by science_man_88

unless that's false [],[] can only return 0 because they have something in common [],set or set,[] have the same reason to return 0 but my code can't work with 0 elements unless I have that outer statement if the statement isn't there it returns 1 (true) that all these are disjoint but everything I've been told makes that a bad result.

Please restate the definition of disjoint sets before proceeding any further. You've hit a conceptual "wrong turn" here.

[CRGreathouse]

This is the empty set (as we're representing it with PARI vectors): []

This is a set containing the empty set as a member: [[]]

This is another set containing the empty set as a member: [1, 2, 3, 4, 5, [], 6]

aredisjoint([], [[]]) should return 1 because they are disjoint: the first set has no members and so there are no common members.

aredisjoint([1, 2, 3, 4, 5, [], 6], [[]]) should return 0 because they aren't disjoint: [] is a member of both.

[science_man_88]

Originally Posted by CRGreathouse

This is the empty set (as we're representing it with PARI vectors): []

This is a set containing the empty set as a member: [[]]

This is another set containing the empty set as a member: [1, 2, 3, 4, 5, [], 6]

aredisjoint([], [[]]) should return 1 because they are disjoint: the first set has no members and so there are no common members.

aredisjoint([1, 2, 3, 4, 5, [], 6], [[]]) should return 0 because they aren't disjoint: [] is a member of both.

point taken.

[science_man_88]

(11:29)>?ispower
ispower(x,{k},{&n}): if k > 0 is given, return true (1) if x is a k-th power, false (0) if not. If k is omitted, return the maximal k >= 2 such that x =
n^k is a perfect power, or 0 if no such k exist. If n is present, and the function returns a non-zero result, set n to the k-th root of x.

(11:31)>ispower(4,,2)
  ***   expected character: '&': ispower(4,,2)
                                            ^--
(11:31)>ispower(4,,&2)
  ***   syntax error, unexpected KINTEGER, expecting KENTRY: ispower(4,,&2)
                                                                         ^--
(11:31)>ispower(4,,{&2})
  ***   syntax error, unexpected KINTEGER, expecting KENTRY: ispower(4,,&2)
                                                                         ^--
(11:31)>ispower(4,,{&2})
  ***   syntax error, unexpected KINTEGER, expecting KENTRY: ispower(4,,&2)
                                                                         ^--
(11:32)>ispower(4,,{2&})
  ***   syntax error, unexpected ')': ispower(4,,2&)
                                                   ^-
(11:32)>ispower(4,,&2)
  ***   syntax error, unexpected KINTEGER, expecting KENTRY: ispower(4,,&2)
                                                                         ^--
(11:32)>ispower(4,2,&2)
  ***   syntax error, unexpected KINTEGER, expecting KENTRY: ispower(4,2,&2)
                                                                          ^--
(11:32)>ispower(4,,&2)
  ***   syntax error, unexpected KINTEGER, expecting KENTRY: ispower(4,,&2)
                                                                         ^--
(11:32)>ispower(4,,2)
  ***   expected character: '&': ispower(4,,2)
                                            ^--
(11:32)>ispower(4,,&)
  ***   syntax error, unexpected ')', expecting KENTRY: ispower(4,,&)
                                                                    ^-
(11:33)>ispower(4,,&"2")
  ***   syntax error, unexpected KSTRING, expecting KENTRY: ispower(4,,&"2")
                                                                          ^--
(11:33)>ispower(4,,&2)
  ***   syntax error, unexpected KINTEGER, expecting KENTRY: ispower(4,,&2)
                                                                         ^--
(11:33)>ispower(4,,{2})
  ***   expected character: '&': ispower(4,,2)
                                            ^--
(11:33)>ispower(4,,&{2})
  ***   syntax error, unexpected KINTEGER, expecting KENTRY: ispower(4,,&2)
                                                                         ^--
(11:33)>ispower(4,,&})
  ***   unexpected closing brace.
(11:33)>ispower(4,,&}
  ***   unexpected closing brace.
(11:33)>ispower(4,,&2}
  ***   unexpected closing brace.
(11:33)>ispower(4,,&2)
  ***   syntax error, unexpected KINTEGER, expecting KENTRY: ispower(4,,&2)
                                                                         ^--
(11:34)>ispower(4,,{2})
  ***   expected character: '&': ispower(4,,2)
                                            ^--
(11:34)>ispower(4,,2)
  ***   expected character: '&': ispower(4,,2)
                                            ^--
(11:34)>ispower(4,,2)

[axn]

? n=0
%12 = 0
? ispower(1024,,&n)
%13 = 10
? n
%14 = 2

You must pass a variable as the third parameter so that the function can pass back the "base".