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# lt, <

Determine less than

## Description

example

A < B returns an array with elements set to logical 1 (true) where A is less than B; otherwise, it returns 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

expand all

### Test Vector Elements

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 =

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     7     9    11     2
```

The result is a subset of the elements in A.

### Replace Elements of Matrix

Create a matrix.

`A = magic(4)`
```A =

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 =

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.

### Compare Values in Categorical Array

Create an ordinal categorical array.

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

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 =

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 =

0     0     1```

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

### Test Complex Numbers

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 =

1.0000 + 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 =

1.0000 + 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.

### Compare Dates

Create a vector of dates.

`A = datetime([2014,05,01;2014,05,31])`
```A =

01-May-2014
31-May-2014```

Find the dates that occur before May 10, 2014.

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

01-May-2014```

## Input Arguments

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### A — Left arraynumeric array | logical array | character array | ordinal categorical array | datetime array | duration array

Left array, specified as a numeric array, logical array, character array, categorical array, datetime array, or duration 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 an ordinal categorical array, the other input can be an ordinal 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. See Compare Categorical Array Elements for more details.

If one input is a datetime array, the other input can be a datetime array, a date string, or a cell array of date strings.

If one input is a duration array, the other input can be a duration array or a numeric array. eq treats each numeric value as a number of standard (86400 s) days.

### B — Right arraynumeric array | logical array | character array | ordinal categorical array | datetime array | duration array

Right array, specified as a numeric array, logical array, character array, categorical array, datetime array, or duration 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 an ordinal categorical array, the other input can be an ordinal 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. See Compare Categorical Array Elements for more details.

If one input is a datetime array, the other input can be a datetime array, a date string, or a cell array of date strings.

If one input is a duration array, the other input can be a duration array or a numeric array. eq treats each numeric value as a number of standard (86400 s) days.