Outputs the given argument using a floating-point representation. The full form is

  ~w,d,k,overflowchar,padchar@F

with the following interpretations

w (nil)

if non-nil, the output will be exactly w characters long,

d (nil)

if non-nil, this is the number of digits output after the decimal point (.),

k (0)

scaling factor - the number is first scaled using this value,

overflowchar (nil)

if non-nil, this character is used when this directive would produce output longer than that specified with the w directive,

padchar (?\s)

character to pad with if w is non-nil and output isn’t wide enough yet,

@

numbers are always output with sign prepended.

An ArgumentError is raised if the argument is not a number or a string that can be converted to a number.