# Tagged Questions

Mathematica pseudo-types Integer, Real, Rational, Complex, String and Symbol, and their use.

10k views

### Struct equivalent in Mathematica?

I really miss having something like a struct in Mathematica. I know of (and regularly use) a couple of programming techniques which feel like a ...
2k views

### How to create strong types?

In a program I'm writing, I create a list of lists, that looks something like this: {{100, {1,2,3,4,5}}, {105, {2,4,6,8}}, {42, {42,39,56}}} I then pass this ...
4k 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 ...
137 views

### V10's TypeSystem - what are these function useful for? [closed]

The symbols in the TypeSystem` context are clearly used for working with Datasets, but they seem powerful. I was hoping that someone could help explain how they work and is they are useful for ...
262 views

### Find all heads a function is defined on

So say I've got a function g defined as follows: g[x_Integer] := x + 1 g[s_String] := s <> "!!!" How would I write a ...
2k views

### Get expression type?

Is there a built in function that distinguishes between different kinds of variables? I mean something like: ...
198 views

### Get information about a stack of images, without plotting it

A very long time ago I used Mathematica for a few months and found it very intuitive. Now for my work I use MatLab. I was just trying some stuff out with Mathematica again and there is something I ...
249 views

### Does there exist any way to add type annotations?

Is there any way to add my own annotations to values or functions in Mathematica? Imagine, for example, that I wanted to annotate a List specifically as a ...
88 views

### Determine return type of CompiledFunction expression

Is there a way to extract the types of the arguments and the return type from a CompiledFunction expression? I am writing a package for code generation (basically a wrapper around CCodeGenerate) where ...
134 views

### Behavior of 1.2 ∈ Rationals changes in v9?

A friend of mine using version 9 recently showed me this: It's strange because in version 8.0.4 1.2 ∈ Rationals does return ...
65 views

### Type error before replacement rule is applied

When I type a <> "0" /. {a -> "1"} I get the error ...
40 views

### Relative factorisation with scalar quantities

I'd like to find a natural way to tell mathematica that a given unknown in a polynomial should be treated as a number, unlike the other variables. Typically I'd like to sum two polynomials in several ...
105 views

### Immutability, Association and typing

I have read the article by Leonid on the question. I am still struggling. I am trying to use Association to inject some pseudo-typing in my code. Here is my ...
123 views

### Datatypes and numbers in Mathematica

I have some questions about numbers in Mathematica: Does Mathematica work with datatypes like int, long, ...
108 views

### Using less memory to store and manipulate specific types

Is there a simple way to use Integer types (in particular, a table of Integer types) that require only 4 or 8 bytes (reps. 32 and 64 bits) representation? It seems that integers in Mathematica have a ...
91 views

### .NET link - index of property

I have a property in .NET Type, which is actually a generic list of objects. When I try access the property using numeric index e.g. 10, this works. However when I iterate through indices using ...
144 views

### How to get the type of an object

I'm looking for a way to get the type of an object: TypeOf["x"] -> String TypeOf[1] -> Integer Or something along those lines.
82 views

### Type declaration for list arguments

How can I make f[n_Integer]=2*n valid for a list of integers? For example: f[nlist_Integer] := 2*nlist[[1]] does not work ...
438 views

### What format to use to store expressions in database?

I am storing lists of expressions into a MySQL database. Each list is of form {_String, {_String, _Real}, _Real} What data format should each column of the ...
121 views

### How to convert a column of a Dataset into a list [closed]

I'm loving the fact that Mathematica has finally implemented the Dataset feature, but I'm still struggling a little with it. I have a Dataset that contains a bunch of functions for different diseases ...
125 views

### Declare type in InputField

Is it possible to declare a type in InputFunction to only accept positive Integers as input? I know i can create an ...
43 views

### Control data type (or precison?) to limit memory usage

I couldn't find the answer to my question, so here it is: I have quite a large table, which I generate in Matlab (for some reasons i use both Matlab and Mathematica, I'd like to use only one of them, ...
53 views

### Compilation error: “Could not complete external evaluation at…”

I'm pretty new to trying to use Compile[], and I just can't see why I'm getting this error. I have two functions to define beforehand; one of them is a bit odd: <...
50 views

### Pattern type and list indexing warnings/errors

I'm new to Mathematica and am trying to implement some simple noise functions in it in hopes of eventually finding an integral for them. This is the interesting part of the code: ...