R: Trigonometric Functions in Degrees

sind,cosd,tand, etc. {pracma} | R Documentation

## Trigonometric Functions in Degrees

### Description

Trigonometric functions expecting input in degrees, not radians.

### Usage

    sind(x)
    cosd(x)
    tand(x)
    cotd(x)
    asind(x)
    acosd(x)
    atand(x)
    acotd(x)
    secd(x)
    cscd(x)
    asecd(x)
    acscd(x)
    atan2d(x1, x2)

### Arguments

`x, x1, x2` | numeric or complex scalars or vectors

### Details

The usual trigonometric functions with input values as scalar or vector in degrees. Note that `tan(x)` with fractional part does not return `NaN` as `tanpi(x)`, but is computed as `sind(x)/cosd(x)`.

For `atan2d` the inputs `x1,x2` can be both degrees or radians, but don't mix! The result is in degrees, of course.

### Value

Returns a scalar or vector of numeric values.

### Note

These function names are available in Matlab, that is the reason they have been added to the ‘pracma’ package.

### See Also

Other trigonometric functions in R.

### Examples

    # sind(x) and cosd(x) are accurate for x which are multiples
    # of 90 and 180 degrees, while tand(x) is problematic.

    x <- seq(0, 720, by = 90)
    sind(x)                     # 0  1  0 -1  0  1  0 -1  0
    cosd(x)                     # 1  0 -1  0  1  0 -1  0  1
    tand(x)                     # 0  Inf  0  -Inf  0  Inf  0  -Inf  0
    cotd(x)                     # Inf  0  -Inf  0  Inf  0  -Inf  0  Inf

    x <- seq(5, 85, by = 20)
    asind(sind(x))              # 5 25 45 65 85
    asecd(sec(x))
    tand(x)                     # 0.08748866  0.46630766  1.00000000  ...
    atan2d(1, 1)                # 45

[Package pracma version 2.0.4 Index]