Practical maths: stick to your knitting

An odd comment by Hinke Osinga’s partner, mathematician Bernd Krauskopf, led her to think about her crotcheting, and realise that she “could crochet the Lorenz manifold,” which led her & others towards representing mathematical figures with stitching work of various kinds.

“Knitting and crocheting are helping us think about math we already know in a different light,” [said] Carolyn Yackel, a mathematician at Mercer University

As Daina Taimina geared up to teach an undergraduate-geometry class as a visiting mathematician at Cornell University, she realised that she had no model for a hyperbolic surface, just for flat & 3D — so she crocheted one. By adding a new stitch every few rows, she was able to produce a hyperbolic plane. David Henderson helped her to prove that the woollen model was indeed hyperbolic.

Knitting a mathematical shape may strike you as odd, but David Hilbert proved that it’s literally impossible to build a smooth model of a hyperbolic surface because of the way it buckles, so crocheting turns out to be well suited to the task.

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new life for an old (FTX) PSU, improved life for one human

the LEDs on this 5m strip happen to emit light centred on a red that does unexpectedly helpful things to (and surprisingly deeply within) a human routinely exposed to it. it has been soldered to a Molex connector, plugged into a TFX power supply from a (retired: the MoBo is cactus) Small Form Factor PC, the assorted PSU connectors (and loose end from the strip) have been taped over. the LED strip cost $10.24 including postage, the rest cost $0, the PSU is running at 12½% of capacity, consumes less power than a laptop plug-pack despite running a fan. trial runs begin today.

every-application-is-part-of-a-toolkit at work

I have a LibreOffice Impress slideshow that I wish to turn into a narrated video. 1. export the slideshow as PNG images (if that is partially broken — as at now — at higher resolutions, Export Directly as PDF then use ‘pdftoppm’ (from the poppler-utils package) to do the same). 2. write a small C program (63 lines including comments) to display those images one at a time, writing a config file entry for Imagination (default transition: ‘cross fade’) based on when the image-viewer application (‘display,’ from the GraphicsMagick suite) is closed on each one; run that, read each image aloud, then close each image in turn. 3. run ‘Imagination’ over the config file to produce a silent MP4 video with the correct timings. 4. run ‘Audacity’ to record speech while using ‘SMPlayer’ to display the silent video, then export that recording as a WAV file. 4a. optionally, use ‘TiMIDIty’ to convert a non-copyright-encumbered MIDI tune to WAV, then import that and blend it with the speech (as a quiet b...

boundaries

pushing the actual boundaries of the physical (not extremes, the boundaries themselves) can often remove barriers not otherwise perceived. one can then often resolve an issue itself, rather than merely stonewalling at the physical consequences of the issue.

Plantagenet Penguinista

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