Ruby: Controlling printing in scientific notation

Question

If I have an extremely long floating point number in Ruby such as:

 x = 123456789012345.to_f

when it is displayed, say, via to_s,

Answer 1

Just for convenience you can also control number of digits after decimal point. So do:

x = 1.234598
"%.3E" % x=> "1.235E+00"

Another neat thing you can do is pad with space from left like this:

x = 1.234 
"%10.3E" % x => " 1.234E+00" 

Answer 2

You can do all sorts of things using the % operator. For example:

x = 123456789012345.to_f
"%f" % x  # => "123456789012345.000000"

y = 1.23
"%E" % y # => "1.230000E+000"

The various options are the same as for the sprintf function.