Extract numbers only

extract only numbers from text file

This is inspired by Peder's READTEXT
and use it to extract numbers only and output an array of only numerical value. The input file can be any numbers mixed with text, symbols,
as long as the numbers are separated from letters at least by a space.
For example, it won't work on 123abc, because computer does not know it should be 1,23 or 12,3, so it will work on 123 abc or 123,abc to extract
a numerical value 123. This is useful for machine generated file often contains some commented text along with values.