# Questions tagged [expression-test]

Questions about Mathematica's predicate functions.

9 questions with no upvoted or accepted answers
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0answers
191 views

### Bug in PositiveDefiniteMatrixQ?

Fixed in 10.1.0. Exists in at least 9.0.1 -- 10.0.2. This seems like a bug in PositiveDefiniteMatrixQ to me: ...
0answers
57 views

### Testing for membership with Bags?

Is there a faster way to test for membership in an Internal`Bag other than unpacking the whole thing like this? ...
0answers
120 views

### How to test solvability of a Diophantine equation?

When applying the BRC theorem I need to test if an equation has a non-zero solution in integers. The equation is of form: $$x^2 + by^2 + cz^2 = 0$$ We could try to directly check if this equation ...
0answers
100 views

### Where is URLExistsQ in version 11?

Searching this function in the doc,it found nothing. Is this function be removed? I want to check weather the url can access from my country. ...
0answers
58 views

### Speed up for SequencePredictorFunction?

From Google Dive: SequencePredictorFunction is here, along with my test data. From pastbin: prediction function and data is here. Using the ...
2answers
107 views

### Specifying that function argument is positive

Struggling with something basic. Suppose when defining f[x_] the outcome depends on Sign[x]. When calling this function, how do I tell Mathematica the sign of the argument? My attempt: ...
0answers
42 views

### How to use === with condition?

I have two expressions, and they are same when k is positive and x is non-zero real number. Below code gives me ...
0answers
40 views

### How to test consistency of two assertions without hacking

Suppose I have a set of assumptions assum = x ∈ Reals && y ∈ Reals and I want to test an assertion like ...
0answers
54 views

### How to check if all the entries in columns of a matrix are equal?

Assume we have the following matrix/tensor. How can I test if the column has the same element? 4-6 and 8-9 columns has the same element. \$ \left( \begin{array}{cccccccccc} \{2,3\} & \{2,3\} &...