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Variations in the literal representation of Pi
The numbers system I am developing attempts to match numeric literals contained in a file against a database of interesting numbers. One of the things I did to quickly build a reasonably sized database...
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Number of digits in floating-point literals
Some of the interesting floating-point literals detected by the numbers program not only look uninteresting but plain wrong. For instance, almost every program I analyze appears to contain a literal...
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Quality comparison of floating-point maths libraries
What is the best way to compare the quality of floating-point math libraries (e.g., sin, cos and log)? The traditional approach for evaluating the quality of an algorithm implementing a mathematical...
View ArticleSearching for inaccurate literals in R
In creating the numbers tool I wanted to be able to do two things, 1) obtain information about what source did by matching the numeric literals it contained against a database of ‘interesting’ values...
View ArticleAutomatically improving code
Compared to 20 or 30 years ago we know a lot more about the properties of algorithms and better ways of doing things often exist (e.g., more accurate, faster, more reliable, etc). The problem with this...
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Optimizing floating-point expressions for accuracy
Floating-point arithmetic is one topic that most compiler writers tend to avoid as much as possible. The majority of programs don’t use floating-point (i.e., low customer demand), much of the analysis...
View ArticleInitial impressions of RangeLab
I was rummaging around in the source of R looking for trouble, as one does, when I came across what I believed to be a less than optimally accurate floating-point algorithm (function R_pos_di in...
View ArticleSuperoptimizers are back in vogue
There has always been the need for a few developer with in-depth knowledge of a particular cpu architecture to sit down and think very hard about how best to implement a snippet of code performing some...
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Tool for tuning the use of floating-point types
A common problem when writing code that performs floating-point arithmetic is figuring out which of the available three (usually) possible floating-point types to use (e.g., float, double or long...
View ArticleTools that help handle floating-point dragons
There be dragons is a common refrain in any discussion involving code containing floating-point. The dragons are not likely to disappear anytime soon, but there has been a lot of progress since my 2011...
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