This post is by my colleague Cosmin Ionita.... 続きを読む >>

Why are manhole covers round? It is so they won't fall through the hole they are intended to cover. They have the same diameter regardless of where it is measured. If the hole has a slightly smaller diameter, it is not possible to orient the cover so that it will fall through. A square or rectangular cover can be turned slightly and it will easily fit through the hole.... 続きを読む >>

Sedona Arizona is a perfect site for the first MathWorks excursion into lifestyle products.... 続きを読む >>

I recently acquired a GPU, a graphics processing unit. It's called a GPU because such processors were originally intended to speed up graphics. But MATLAB uses it to speed up computation. Let's see how the gpuArray object benchmarks on my machine. I have been doing computer benchmarks for years. I like to do profiles where I vary the size of a task and see how the amount of memory required affects performance. I always learn something unexpected when I do these profiles. Ben Todoroff is on the MathWorks Parallel Processing team. Last year he contributed #34080, gpuBench to the MATLAB Central File Exchange. He has been able to compare several different GPUs. I am going to consider the performance of only one GPU, but in more detail. Important note. This is only about double precision. Single precision is another story. ... 続きを読む >>

My MATLAB® program, amaze, generates mazes by combining old friends, numgrid and delsq, with a new friend, the graph object. Let's see how we make this example maze.... 続きを読む >>

For the past month I have been working with the variable format 16-bit floating point arithmetic that I described in this post. It has been frustrating work. I have found that the limited precision and limited range of half precision make it barely usable for the kind of experiments with matrix computation that I like to do. In this post I will describe a few of these experiments.... 続きを読む >>

In a comment following my post about half-precision arithmetic, "Raj C" asked how the parameters for IEEE Standard 754 floating point arithmetic were chosen. I replied that I didn't know but would try to find out. I called emeritus U. C. Berkeley Professor W. (Velvel) Kahan, who was the principle architect of 754. Here is what I learned.... 続きを読む >>

A year and a half ago I wrote a post about "half precision" 16-bit floating point arithmetic, Moler on fp16. I followed this with a bug fix, bug in fp16. Both posts were about fp16, defined in IEEE standard 754. This is only one of 15 possible 16-bit formats. In this post I am going to consider all 15.... 続きを読む >>

VAXBARN Restores Vibrating Membrane on Ardent Titan dore_frame This is a short post to point to a web site in the Netherlands, VAXBARN. The site proprietor, Camiel Vanderhoeven, is assembling a... 続きを読む >>

Mandelbrot Brings Season's GreetingsMandelbrot sports a new red, green and gold colormap to celebrate the holidays. old_mandelbrot holiday_mandelbrot Available in Version 4.10 of Cleve's... 続きを読む >>