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# ne, ~=

Determine inequality

## Description

example

A ~= B returns a logical array with elements set to logical 1 (true) where arrays A and B are not equal; otherwise, it returns logical 0 (false). The test compares both real and imaginary parts of numeric arrays. ne returns logical 1 (true) where A or B have NaN or undefined categorical elements.

eq(A,B) is an alternative way to execute A ~= B, but is rarely used. It enables operator overloading for classes.

## Examples

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### Inequality of Two Vectors

Create two vectors containing both real and imaginary numbers.

```A = [1+i 3 2 4+i];
B = [1 3+i 2 4+i];```

Compare the two vectors for inequality.

`A ~= B`
```ans =

1     1     0     0```

The ne function tests both real and imaginary parts for inequality, and returns logical 1 (true) where one or both parts are not equal.

### Find Characters in String

Create a string of characters.

`M = 'masterpiece';`

Test the string for the presence of a specific character using ~=.

```M ~= 'n'
```
```ans =

1     1     1     1     1     1     1     1     1     1     1```

The value of logical 1 (true) in the vector indicates the absence of the character 'n'. The character is not present in the string.

### Find Values in Categorical Array

Create a categorical array.

`A = categorical({'heads' 'heads' 'tails'; 'tails' 'heads' 'tails'})`
```A =

The array has two categories: 'heads' and 'tails'.

Find all values not in the 'heads' category.

`A ~= 'heads'`
```ans =

0     0     1
1     0     1```

A value of logical 1 (true) indicates a value not in the category. Since A only has two categories, A ~= 'heads' returns the same answer as A == 'tails'.

Compare the rows of A for inequality.

`A(1,:) ~= A(2,:)`
```ans =

1     0     0```

The function returns logical 1 (true) where the rows have unequal category values.

### Compare Floating-Point Numbers

Some floating-point numbers cannot be represented exactly in binary form. This leads to small differences in results that the ~= operator reflects.

Perform a few subtraction operations on a floating-point number and store the result in C.

```C = 0.5-0.4-0.1
```
```C =

-2.7756e-17
```

Intuitively, C should be equal to exactly 0. Its small value is due to the nature of floating-point arithmetic.

Compare C to zero for inequality.

`C ~= 0`
```ans =

1```

The result is logical 1 (true).

Compare floating-point numbers using a tolerance, tol, instead of ~=.

```tol = eps;
abs(C-0) > tol```
```ans =

0
```

The two numbers, C and 0, are closer to one another than two consecutive floating-point numbers. They are essentially equal.

## Input Arguments

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### A — Left arraynumeric array | logical array | character array | categorical array

Left array, specified as a numeric array, logical array, character array, or categorical array. Inputs A and B must be the same size unless one is a scalar. A scalar input expands into an array of the same size as the other input.

If one input is a categorical array, the other input can be a categorical array, a cell array of strings, or a single string. A single string expands into a cell array of strings of the same size as the other input. If both inputs are ordinal categorical arrays, they must have the same sets of categories, including their order. If both inputs are categorical arrays that are not ordinal, they can have different sets of categories. See Compare Categorical Array Elements for more details.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical | char
Complex Number Support: Yes

### B — Right arraynumeric array | logical array | character array | categorical array

Right array, specified as a numeric array, logical array, character array, or categorical array. Inputs A and B must be the same size unless one is a scalar. A scalar input expands into an array of the same size as the other input.

If one input is a categorical array, the other input can be a categorical array, a cell array of strings, or a single string. A single string expands into a cell array of strings of the same size as the other input. If both inputs are ordinal categorical arrays, they must have the same sets of categories, including their order. If both inputs are categorical arrays that are not ordinal, they can have different sets of categories. See Compare Categorical Array Elements for more details.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical | char
Complex Number Support: Yes