Questions about Mathematica's predicate functions.

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18
votes
4answers
661 views

Why does Mathematica claim there is no even prime?

I wonder if this is a bug, or if I'm misunderstanding something: Exists[n, EvenQ[n] && PrimeQ[n]] // Resolve (* ==> False *) So if I interpret this ...
18
votes
2answers
426 views

Implementing a safe ValueQ that does not evaluate its argument

Mathematica has a built-in function ValueQ. Quoting the docs, ValueQ[expr] gives True if ...
16
votes
9answers
844 views

How do you check if there are any equal arguments(even sublist) in a list?

I would like to set up a function which has to return True if at least two arguments of a given List are equal. So if I give {1,4,6,2} to the function it has to ...
14
votes
1answer
457 views

_?NumericQ equivalent for lists

A few months ago I got a simple answer (see: 1 ) to the question of how to force numeric evaluation during use of functions such as NMinimize - namely the use of _?NumericQ in the argument list. I ...
13
votes
3answers
192 views

How can I test properties of a symbol from the string name without the symbol completely evaluating

Suppose I have a few symbols, one of which has a value: {abc1, abc2 = 5, abc3}; I can use Names to get the list of names, as ...
12
votes
5answers
687 views

How to check if an expression is a real-valued number

What is a simple, fast way to test whether an expression is a real-valued number? I ask since there is no RealQ function. If we call this test ...
12
votes
2answers
166 views

How can one write a robust ListableQ function?

I would like to have a test that determines if a particular function is Listable. In the case of Symbols this is merely a matter of checking Attributes. ...
10
votes
5answers
1k views

Fastest square number test

What is the fastest possible square number test in Mathematica 7, both for machine size and big integers? I presume in version 8 the fastest will be a dedicated C LibraryLink function.
10
votes
1answer
217 views

Why does Assuming[x > 0, TrueQ[x > 0]] return False?

Assuming[x>0,TrueQ[x>0]] should, as I understand it, test TrueQ[x>0] after assuming ...
9
votes
2answers
363 views
8
votes
2answers
477 views

How does Mathematica decide that Log[2,8] is integer?

At school we learned that $\log_b(x)=\log(x)/\log(b)$, which is implemented in Mathematica as Log[b, x], but the results are different. ...
7
votes
3answers
141 views

Checking through an expression

I am writing a code that manipulates expressions that contains functions with an arbitrary number of arguments. An example expression is ...
6
votes
2answers
207 views

Why does PolynomialQ[x^n, x] return False?

From what I can see PolynomialQ will return False whenever some exponent is another variable such as here: ...
5
votes
2answers
266 views

Why is an integer not considered as a real?

Please consider the following: zeros={0.,0}; data={1, 0., 0}; DeleteCases[data, #]&/@zeros Head/@zeros (*{Real, Integer}*) (*{{1, 0}, {1, 0.}}*) For my ...
5
votes
1answer
114 views

lists of conditions

I have got coordinates in two list of Latitude and Longitude and would like to check if those coordinates are in a certain grid Example lists are: ...
4
votes
1answer
204 views

How to check if a given expression is an “explicit algebraic number”?

The documentation for PossibleZeroQ says: With the setting Method...
4
votes
1answer
101 views

How can I test properties of a symbol without unwanted evaluation

Problem How to get the head, size, dimensions, etc. of a symbol without evaluating it? Since Mathematica does not allocate fix storage space and type to symbols it is not trivial to query runtime ...
3
votes
2answers
150 views

Finding similar expressions in list

I have a function that returns to me lists of expressions, like: ...
2
votes
2answers
95 views

Using FreeQ with implicit functions

In Mathematica 7, I want to determine whether a list of free of numbers greater than 1 or not. It seems like using FreeQ would be a concise way to do this: ...
2
votes
2answers
78 views

Testing for arbitrary algebraic expression in given variable

I want to test, for example with MatchQ, if the argument of a function is an arbitrary expression in a single or several variables whose names can be assumed to be ...
2
votes
1answer
100 views

How to work with the symbol EndOfFile? [duplicate]

How to work with the symbol EndOfFile? I want to use the EndOfFile symbol to determine when my control structure reaches the end ...
1
vote
2answers
153 views

How to pick a solution from a list of solutions using a test?

I have a list of solutions that depends on a parameter b3 and I'd like to get the solution for which the x value is minimal when ...
1
vote
2answers
345 views

Faster way to test if an expression equals zero

I want to test if expressions (mix of variables, functions and numbers) are zero valued, as fast as possible, and PossibleZeroQ is sometimes very slow. One solution ...
0
votes
1answer
56 views

What is the most elegant way to see if an expression is affected by a certain symbol? [duplicate]

Possible Duplicate: Determine whether some expression contains a given symbol Let's say I have some expression: sample = {1, 1/q, f[m]} And I want to ...