• Is the input data good? Garbage in, garbage out!
  • Is the data source authoritative? ( Don't trust it!)

  • Was the data measured accurately?

  • How much noise does the data have?

  • Was the data recorded accurately?

  • Does the data mean what it is alleged to mean?

• Is the algorithm correct?

• Is the algorithm an accurate model of reality?

• Are the answers numerically accurate?

• Is the data represented accurately?
  • 32-bit int: 9 decimal digits
  • 64-bit long: 19 decimal digits
  • 32-bit float: 7 decimal digits ( avoid! )
    Patriot missile: inaccurate float conversion caused range gate error: 28 killed, 98 injured.
  • 64-bit double: 15+ decimal digits
  • Ariane 5: 64-bit double converted to 16-bit int: overflowed, rocket exploded, $500 million loss.

Contents    Page-10    Prev    Next    Page+10    Index