# lt, <

Determine less than

## Syntax

``A < B``
``lt(A,B)``

## Description

example

````A < B` returns an array with elements set to logical 1 (`true`) where `A` is less than `B`; otherwise, the element is logical `0` (`false`). The test compares only the real part of numeric arrays. `lt` returns logical `0` (`false`) where `A` or `B` have NaN or undefined `categorical` elements.```
````lt(A,B)` is an alternate way to execute `A < B`, but is rarely used. It enables operator overloading for classes.```

## Examples

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Determine if vector elements are less than a given value.

Create a numeric vector.

`A = [1 12 18 7 9 11 2 15];`

Test the vector for elements that are less than `12`.

`A < 12`
```ans = 1x8 logical array 1 0 0 1 1 1 1 0 ```

The result is a vector with values of logical `1` (`true`) where the elements of `A` satisfy the expression.

Use the vector of logical values as an index to view the values in `A` that are less than `12`.

`A(A < 12)`
```ans = 1×5 1 7 9 11 2 ```

The result is a subset of the elements in `A`.

Create a matrix.

`A = magic(4)`
```A = 4×4 16 2 3 13 5 11 10 8 9 7 6 12 4 14 15 1 ```

Replace all values less than `9` with the value `10`.

`A(A < 9) = 10`
```A = 4×4 16 10 10 13 10 11 10 10 9 10 10 12 10 14 15 10 ```

The result is a new matrix whose smallest element is `9`.

Create an ordinal categorical array.

```A = categorical({'large' 'medium' 'small'; 'medium' ... 'small' 'large'},{'small' 'medium' 'large'},'Ordinal',1)```
```A = 2x3 categorical large medium small medium small large ```

The array has three categories: `'small'`, `'medium'`, and `'large'`.

Find all values less than the category `'medium'`.

`A < 'medium'`
```ans = 2x3 logical array 0 0 1 0 1 0 ```

A value of logical `1` (`true`) indicates a value less than the category `'medium'`.

Compare the rows of `A`.

`A(1,:) < A(2,:)`
```ans = 1x3 logical array 0 0 1 ```

The function returns logical `1` (`true`) where the first row has a category value less than the second row.

Create a vector of complex numbers.

`A = [1+i 2-2i 1+3i 1-2i 5-i];`

Find the values that are less than `3`.

`A(A < 3)`
```ans = 1×4 complex 1.0000 + 1.0000i 2.0000 - 2.0000i 1.0000 + 3.0000i 1.0000 - 2.0000i ```

`lt` compares only the real part of the elements in `A`.

Use `abs` to find which elements are within a radius of `3` from the origin.

`A(abs(A) < 3)`
```ans = 1×3 complex 1.0000 + 1.0000i 2.0000 - 2.0000i 1.0000 - 2.0000i ```

The result has one less element. The element `1.0000 + 3.0000i` is not within a radius of `3` from the origin.

Create a vector of dates.

`A = datetime([2014,05,01;2014,05,31])`
```A = 2x1 datetime 01-May-2014 31-May-2014 ```

Find the dates that occur before May 10, 2014.

`A(A < '2014-05-10')`
```ans = datetime 01-May-2014 ```

## Input Arguments

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Operands, specified as scalars, vectors, matrices, or multidimensional arrays. Inputs `A` and `B` must either be the same size or have sizes that are compatible (for example, `A` is an `M`-by-`N` matrix and `B` is a scalar or `1`-by-`N` row vector). For more information, see Compatible Array Sizes for Basic Operations.

You can compare numeric inputs of any type, and the comparison does not suffer loss of precision due to type conversion.

• If one input is an ordinal `categorical` array, the other input can be an ordinal `categorical` array, a cell array of character vectors, or a single character vector. A single character vector expands into a cell array of character vectors 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. See Compare Categorical Array Elements for more details.

• If one input is a `datetime` array, the other input can be a `datetime` array, a character vector, or a cell array of character vectors.

• If one input is a `duration` array, the other input can be a `duration` array or a numeric array. The operator treats each numeric value as a number of standard 24-hour days.

• If one input is a string array, the other input can be a string array, a character vector, or a cell array of character vectors. The corresponding elements of `A` and `B` are compared lexicographically.

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

## Compatibility Considerations

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Behavior changed in R2016b

Behavior changed in R2020b