# conj

Complex conjugate of symbolic input

## Syntax

``conj(x)``

## Description

example

````conj(x)` returns the complex conjugate of `x`. Because symbolic scalar variables are complex by default, unresolved calls, such as `conj(x)`, can appear in the output of `norm`, `mtimes`, and other functions. For details, see Use Assumptions on Symbolic Variables.For complex `x`, ```conj(x) = real(x) - i*imag(x)```.```

## Examples

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Compute the conjugate of numeric input.

`conj(1+3i)`
```ans = 1.0000 - 3.0000i```

Compute the conjugate of symbolic input.

```syms x f = x^2; fConj = conj(f)```
```fConj = conj(x)^2```

Convert symbolic output to double by substituting for `x` with a number by using `subs`, and then using `double`.

```fConj = subs(fConj,x,1+2i); % x is 1+2i fConj = double(fConj)```
```fConj = -3.0000 - 4.0000i```

If the input is real, `conj` returns the input instead of an unresolved call. Assume `x` is real and find its conjugate. `conj` returns `x` instead of `conj(x)`, as expected.

```syms x assume(x,'real') conj(x)```
```ans = x```

Clear the assumption for further computations.

`assume(x,'clear')`

## Input Arguments

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Input, specified as a number, vector, matrix, or array, or a symbolic number, scalar variable, matrix variable (since R2021a), array, function, or expression.

## Version History

Introduced before R2006a