11.1.1 Numeric Functions
  Numeric functions generally return a result of the same data
  type as the function's parameter. For example, if you pass
  a DOUBLE argument to any of the trigonometric functions,
  they return a DOUBLE result.

  If the format of a BASIC function specifies an argument
  of a particular data type, BASIC converts the actual ar-
  gument supplied to the specified data type. For example, if
  you supply an integer argument to a function that expects
  a floating-point number, BASIC converts the argument to a
  floating-point number. Floating-point arguments that are
  passed to integer functions are truncated, not rounded.

  The following sections discuss the BASIC built-in numeric
  functions.