# Overview
`NumericMatrix` and `LogicalMatrix` are two of the many matrix classes for different data types provided by R in Rcpp.

**Rcpp** is a package that integrates R and C++. It provides both R functions and C++ classes.

## `NumericMatrix`

The **`NumericMatrix`** is a type of matrix that takes a *numerical vector value* as a parameter, and the elements in it are `double`.

### Example

Let's discuss this with a code example below:

////Including Rcpp library
#include <Rcpp.h>
using namespace Rcpp;
// [[Rcpp::export()]]
Rcpp::NumericMatrix myNumericMatrix() {
    // Create a matrix with 3 rows and 3 columns
    Rcpp::NumericMatrix x(3, 3);
    return(x);
}

Rcpp::sourceCpp('/usercode/main.cpp')
myNumericMatrix()

Rcpp

### Explanation

The code above is for the `NumericMatrix`, where the elements of the matrix are numerical values. 
- Line 1: We include the `Rcpp` library. 
- Line 4: We export `Rcpp` into this code file. 
- Line 5: We add the function header. 
- Line 7: We create a matrix of 3 columns and 3 rows. We initialize them with a `0` value, which is a `double` data type in C++. By default, it initializes the matrix with all *0* entries.
- Line 8: We return the created matrix.

## `LogicalMatrix`

On the other hand, we have `LogicalMatrix`. In **`LogicalMatrix`**, the function gets a *logical vector* where the elements are of the `bool` data type.

### Example 

Let's discuss this in detail with the code example below.

//Including Rcpp library
#include <Rcpp.h>
using namespace Rcpp;
// [[Rcpp::export()]]
Rcpp::LogicalMatrix myLogicalMatrix() {
    // Create a matrix with 3 rows and 3 columns
    Rcpp::LogicalMatrix x(3, 3);
    return(x);
}

Rcpp::sourceCpp('/usercode/main.cpp')
myLogicalMatrix()

### Explanation

The code given above is for the `LogicalMatrix`, where the elements of the matrix are logical values. 

- Line 1: We include the `Rcpp` library. 
- Line 4: We export `Rcpp` into this code file. 
- Line 5: We add the function header. 
- Line 7: We create a matrix of 3 columns and 3 rows. We initialize them with a `FALSE` value which is of the `bool` data type. By default, it initializes the matrix with all `FALSE` entries. 
- Line 8: We return the created matrix.

> **Note**: There are two files in our code. One is an `.r` file named `main.r`, and the other one is a `.cpp` file named `main.cpp`. The major part of code is written in the `.cpp` file, while the `.r` file calls the function. Both the files are mutually integrated with each other using `sourceCpp`.

What are NumericMatrix and LogicalMatrix in Rcpp?

Overview

NumericMatrix

Example

Explanation

LogicalMatrix

Example

Explanation

`NumericMatrix`

`LogicalMatrix`