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 Post subject: Mathematical FormulaePosted: Fri, 06-09-13, 12:45 GMT

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4534
Location: Hamburg, Germany
In our CM forums the chances are not so small that a decent rendering of mathematical formulae is urgently desired.

Unfortunately, the LaTeX module is said not to work very reliably for phpbb3 forums.
So what to do?

This problem is also quite familiar to me professionally:

Theoretical research physicists have to give plenty of talks with formulae. In the olden days we all used LaTeX for writing them on the foils. But if one has to give e.g. review talks at conferences that usually involve many pictures as well, the easiness of placing them with MS Powerpoint is also very much appreciated. Since the intrinsic capability of composing formulae in Powerpoint is meager (as to be expected ), one also needs some extra tricks here...

What works pretty well is the following recipe:

Use e.g. an external LaTeX installation to compose your formulae and produce a PDF file thereof. Alternatively, use someone elses formulae in a PDF file or (like me) dump Maple/Mathematica workfiles into PDF. Let us simply assume you have a PDF file containing the formulae in question...

Then you load these into your PDF reader and magnify the display to 200 (- 400) % (Try out best setting once. This is crucial!!). Use the PDF reader's image selection cursor, mark appropriate rectangles containing your formulae and copy the stuff to your clipboard (image mode NOT text mode!).

If this is done, load the GIMP and paste your fomula images from the clipboard onto the GIMP canvas. If you are in a hurry, just save each formula into a .JPG file. Some readers (Linux) also allow to save the selected images directly into JPG files (without using the clipboard). With the JPG format you'll get a white background behind the formulae, since JPG's don't support transparency!

If you are more of a perfectionist, do this with the formula display in GIMP:

With a click you can simply place the current background color into the Alpha channel which simply means that you cleanly generate a transparent background! In order to retain the transparency in your saved file, you need to use the lossless PNG format.

With mouse_right click on colors->color to Alpha...In the upcoming dialog, chose your current background color (white) and click OK. Then the background of your formula turns transparent. This also works fine with anti-aliased fonts! Save the formula as a PNG. If you can upload the formulae to some server (e.g. ibiblio, ...) then you may avoid the built-in "attachment" tool and get e.g. the following pretty good quality with a color-matched background:

The appearance of the much quicker JPG method you can examine e.g. in my recent galactic halo stars post, viewtopic.php?f=11&t=544#p10516

Fridger

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 Post subject: Re: Mathematical FormulaePosted: Tue, 10-09-13, 18:15 GMT

Joined: Fri, 02-07-10, 11:20 GMT
Posts: 64

1) Type in the LaTeX
2) Select png, appropriate resolution setting
3) Right click on equation and click "copy image URL" (or its equivalent on your OS and browser)
4) Place that url inbetween the img tags in the post.

$\dpi{120} ds^2 = -\left(1-\frac{2GM}{r}\right)dt^2+\left(1-\frac{2GM}{r}\right)^{-1}dr^2+r^2(d\theta^2+\sin^2\theta d\varphi^2)$

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 Post subject: Re: Mathematical FormulaePosted: Wed, 11-09-13, 8:37 GMT

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4534
Location: Hamburg, Germany
Excellent!

Perhaps it's worth adding that each of the two methods has its advantages, depending on the kind of application:

My method above is very handy, if you got the formulae already (e.g. after PDF conversion from Maple / Mathematica or in a PDF-formatted paper or (review) talk of yourself or others, etc).

If you still have to compose the LaTeX part, then such a editor (with online formula display) is unbeatable.

Note also that in the LaTeX editor quoted by Hungry, you may select whether you want transparent or some colored background and also what type of font and which font size you prefer!

Fridger

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 Post subject: Re: Mathematical FormulaePosted: Wed, 11-09-13, 9:57 GMT

Joined: Thu, 30-08-07, 22:52 GMT
Posts: 2726
Location: France, South, not far from Montpellier
t00fri wrote:

Yes of course!

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 Post subject: Re: Mathematical FormulaePosted: Wed, 11-09-13, 10:03 GMT

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4534
Location: Hamburg, Germany
ElChristou wrote:
t00fri wrote:

Yes of course!

Hi hi.

But it's a famous formula not unrelated to what we are doing here...

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 Post subject: Re: Mathematical FormulaePosted: Wed, 11-09-13, 23:56 GMT

Joined: Fri, 02-07-10, 11:20 GMT
Posts: 64
I'm not exactly sure but it looks like the Schwarzschild metric to me.

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 Post subject: Re: Mathematical FormulaePosted: Thu, 12-09-13, 9:05 GMT

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4534
Location: Hamburg, Germany
Hungry4info wrote:
I'm not exactly sure but it looks like the Schwarzschild metric to me.

Yes, it's the metric of a Schwarzschild Black Hole of mass M. G is Newton's gravitational constant and units of lightspeed c = 1 are used as usual.

Fridger

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