# atan(x): Trigonometric ArcTangent¶

Trigonometric arctangent (inverse arctangent) function.

## Declaración¶

### Sintaxis¶

retval = atan(x)
elemental real(p) function atan(x)
elemental complex(p) function atan(x)


### Argumentos¶

x the input value, can be real or complex; less than or equal to 1.

### Valores devueltos¶

The returned value has the kind of the input value and TYPE may be real or complex.

## Descripción¶

atan(x) computes the arctangent of the argument x.

The arc tangent is the inverse function of the arctangent function. It is commonly used in trigonometry to find the angle when the lengths of the opposite side of a right triangle and base are known, i.e., perpendicular and base length.

## Tipos¶

Supported argument types float, double, complex float, complex double.

interface atan
module procedure satan, datan, catan, zatan
end interface

contains

interface
elemental real(sp) function satan(x)
real(sp), intent(in) :: x
end function

elemental real(dp) function datan(x)
real(dp), intent(in) :: x
end function

elemental complex(sp) function catan(x)
complex(sp), intent(in) :: x
end function

elemental complex(dp) function zatan(x)
complex(dp), intent(in) :: x
end function
end interface


## Ejemplos¶

program intrinsics_atan
implicit none
integer, parameter :: arg_x = kind(0.0)
real(arg_x) :: x1
real :: retval_x
real :: arg_x
retval_x = atan(0.84147098)
print *, ret_val_x
retval_x = atan(x1)
print *, ret_val_x
end program


Result:

0.699521642
0.699521642


asin, acos.