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Questions tagged [data-types]

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

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2
votes
0answers
49 views

Provide definition to FunctionCompile

I recently upgraded to Mathematica 12, and I've been excited to explore new features such as FunctionCompile, which produces llvm code. I tried compiling the ...
1
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0answers
24 views

SemanticImport changes “string” type to “quantity” type--how to change during import or after import?

This question may overlap with other questions about the quirks of SemanticImport, but I don't see this specific wrinkle on StackExchange and I hope it will be a simple answer to help me and others ...
7
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1answer
115 views

What is an example of of idiomatic “typed” WolframScript?

I'd like to make my own "typed function" in WolframScript. Suppose the type we desire is called money, and we'd like to make a function called ...
10
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2answers
556 views

Make symbols atomic, without losing their type

So, I'd like to define a matrix M, that does not decompose into it's constituents when I do things like Tr[M], but I also want it's type to be retained. (By type, ...
0
votes
0answers
56 views

CompiledFunction::ctfa - Argument should be a rank 4 tensor of machine-size real number

Dear Mathematica community, I got the following error line: CompiledFunction::ctfa "Argument {<<1>>} at position 1 should be a rank 4 tensor of machine-size real number" This is my function:...
0
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1answer
51 views

Who knows what happened in this code? (The difference between 3 and 3.)

I have a problem in my code. This code produces two different results when we use GM = {{Sqrt[3.], 0}, {-Sqrt[3], 3}/2} and GM = {{Sqrt[3], 0}, {-Sqrt[3], 3}/2}, where I just use Sqrt[3] instead of ...
15
votes
1answer
257 views

NumericArray versus PackedArray in MMA12

I just tried to understand the differences between NumericArray and PackedArray in MMA12. The memory footprint of a ...
10
votes
1answer
246 views

Is it possible to restrict the arguments for a function to a specific entity type?

I'm trying to wrap my head around how to work with Mathematica for building (computable) domain specific knowledge. One particular thing I didn't quite understand is how to create symbols for ...
22
votes
2answers
1k views

Why no RationalQ or RealQ?

Interesting pattern came up as I go through the homework replies of my students. Why is there no RationalQ or RealQ? We have <...
2
votes
1answer
44 views

Data Type that can contain multiple data types

In MATLAB one can use cell arrays and structures to "hold" data of different types. For example, one can define a cell array in which the first cell contains an array, the second a differently sized ...
4
votes
1answer
305 views

How to convert entity to string?

I have an entity city. For example, I run {city} = GeoNearest["City", GeoPosition[{41.8, -87.7}]] and then I got The entity "...
12
votes
1answer
176 views

Is it possible to set multiple type to a variable?

Consider this f[x_Real] := 2 x f[1] f[1] f[1.0] 2.0 I want ...
1
vote
2answers
84 views

How to create an unevaluated command like Sequence

I work with linear combinations of graphs, $$c_1 G_1 + c_2 G_2 + \dotsc,$$ and I want to represent them in my Mathematica code. I represent graphs as adjacency matrices, e.g. ...
3
votes
1answer
135 views

How to define “typed” objects and their operator specializations?

I've defined a primitive sort of type system where my objects are defined as lists with an associated identifier: ...
1
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0answers
39 views

Integer data type mapping problem with SQLInsert in DatabaseLink package

I am working with a following SQL table named "ticket". Now let's see the data types for the columns. ...
4
votes
1answer
218 views

Specify Variable Size

Is there an easy way to specify the variable size and still use them as variables more specifically for the .NETLink? Something like the following I am thinking. ...
1
vote
1answer
108 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, ...
4
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2answers
7k 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.
5
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1answer
306 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 ...
1
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0answers
145 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: <...
17
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0answers
211 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 ...
1
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0answers
62 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: ...
4
votes
2answers
74 views

Type error before replacement rule is applied

When I type a <> "0" /. {a -> "1"} I get the error ...
7
votes
1answer
3k 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 ...
3
votes
1answer
217 views

Datatypes and numbers in Mathematica

I have some questions about numbers in Mathematica: Does Mathematica work with datatypes like int, long, ...
4
votes
1answer
47 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 ...
2
votes
1answer
89 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 ...
1
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0answers
76 views

How can I perfect this game for Wolfram Demonstration publication? [closed]

When the messages change the window inactivates, and when I try to host an interactive CDF on my site it turns red and says something about numbers having to be scaled or offset. Any help? I'm ...
2
votes
1answer
392 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 ...
13
votes
1answer
11k views

Get expression type?

Is there a built in function that distinguishes between different kinds of variables? I mean something like: VariableType[ 123 ] Number ...
5
votes
1answer
126 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 ...
12
votes
3answers
313 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 ...
3
votes
1answer
222 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 ...
5
votes
1answer
138 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 ...
3
votes
1answer
120 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 ...
0
votes
1answer
717 views

Mathematica command for type checking?

I have a program where users can enter mathematica commands that can evaluate to any of the standard numeric types (complex, real, int, etc.), or to boolean values. Moreover the users can enter ...
22
votes
6answers
9k 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 ...
2
votes
3answers
814 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 ...
38
votes
4answers
3k 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 ...
111
votes
7answers
14k 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 ...
6
votes
3answers
315 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 ...