Provides the functionality of cos, but for input angles measured in degrees (not radians).
Usage
cos.d(theta = 0)
Arguments
theta
A numeric angular measurement in degrees from north.
Value
Returns a numeric value for the cosine of the specified angular measurement
Details
Since the R default is to compute trigonometric functions on angular measurements stored in radians, this simple function performs the conversion from degrees, reducing the need to do so a priori, outside the function.