Monthly Archives: March 2013

How Accurate Are Spreadsheets in the Cloud?

For a vector with elements the sample variance is , where the sample mean is . An alternative formula often given in textbooks is . This second formula has the advantage that it can be computed with just one pass … Continue reading

Posted in software | Tagged | 5 Comments

SIAM Conference on Computational Science and Engineering 2013

As predicted in my my preview post, this conference, held on the Boston waterfront, proved to be SIAM’s largest ever, with 1378 attendees. Over 1000 presentations were given in up to 20 parallel minisymposia at a time, but this did … Continue reading

Posted in conferences | Tagged , | 1 Comment

Tiny Relative Errors

Let and be distinct floating point numbers. How small can the relative difference between and be? For IEEE double precision arithmetic the answer is , which is called the unit roundoff. What if we now let and be vectors and … Continue reading

Posted in research | Tagged , , | Leave a comment