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### Macro photography with reversed lens

I had forgotten the simple joys of experimenting with cameras. Some of you will recall the old trick of reversing your lens to obtain macro photos. Here I simply took my 18-55 kit lens, reversed it, set it to 18mm and took a photo of my laptop monitor. I aimed it at a white part of the screen and you can see the three sub pixels per real pixel which combine together to give the illusion of white.

### Python: Multiprocessing: passing multiple arguments to a function

Write a wrapper function to unpack the arguments before calling the real function. Lambda won't work, for some strange un-Pythonic reason.

import multiprocessing as mp def myfun(a,b): print a + b def mf_wrap(args): return myfun(*args) p = mp.Pool(4) fl = [(a,b) for a in range(3) for b in range(2)] #mf_wrap = lambda args: myfun(*args) -> this sucker, though more pythonic and compact, won't work p.map(mf_wrap, fl)

### Flowing text in inkscape (Poster making)

You can flow text into arbitrary shapes in inkscape. (From a hint here).

You simply create a text box, type your text into it, create a frame with some drawing tool, select both the text box and the frame (click and shift) and then go to text->flow into frame.

UPDATE:

The omnipresent anonymous asked:
Trying to enter sentence so that text forms the number three...any ideas?
The solution:
Type '3' using the text toolConvert to path using object->pathSize as necessaryRemove fillUngroupType in actual text in new text boxSelect the text and the '3' pathFlow the text

### Latex math: Vertical bar

Like that used for indicating the evaluation of integrals between limits:

\bigg|

as in

\frac{\rho}{4\pi}\left(-\frac{1}{r}\right)\bigg|_{r_{0}}^{\infty}

from a hint here from robphy