# Does this math formula with $1/PI\begin{cases}^\infty_{-\infty}\end{cases}$ mean anything?

I happened upon an image on the Internet

(source: news.com.au)

and I wondered whether the math on the chalkboard means anything. Using Google's image search, I found three other related images.

(source: nees.org)

Piecing together the math from the various angles shows some mismatched grouping symbols.

My question: Ignoring the possible typos, does the "math" mean anything? Or is this an example of stock photography trying to appear mathy?

• It's almost an integral, but written weirdly.
– user223391
May 22, 2015 at 16:26
• Looks like someone copied something they didn't understand. If instead of the curly bracket $\{$ they had written an integral sign $\int$, then they appear to be something like the formulae for Fourier series/transform. May 22, 2015 at 16:26
• You'd have to ask the guy pointing very proudly at $$1/PI\big\{_{-\infty}^\infty\ f(t) \sin ty\ dt,$$ I think he just discovered its meaning. May 22, 2015 at 16:28
• So the best suggestion is to replace $\{$ with $\int$ and $PI$ with $\pi$. May 22, 2015 at 16:50
• I remember I have seen an OCR software which have mistaken the integral sign $\int$ as the parenthesis when extracting math from old book. So the { part doesn't look too strange to me. In fact, the $acy |$ on the second line also looks like an OCR mistake to me (the original should be $a(y)$). May 22, 2015 at 17:05

## 2 Answers

It's safe to say that the math doesn't mean anything. No branch of mathematics or science or anything else uses the symbol $\{$ for an integral sign, and there are mismatched parentheses.

Googling fourier "a(y)" "b(y)" yields this first hit:

• +1 It looks like this is the original text for what's on the board. What the board is showing is the output of the text under OCR. May 22, 2015 at 17:24
• while I am happy to have gotten 180 points for essentially nothing, this is the right answer and should be accepted! May 22, 2015 at 20:04
• Very nice find via Google! May 23, 2015 at 18:12
• Thanks @hunter ! Your endorsement has boosted my rep past the 2k threshold May 23, 2015 at 20:46