Is there a calculator with LaTeX-syntax?

Question

When I write math in LaTeX I often need to perform simple arithmetic on numbers in my LaTeX source, like 515.1544 + 454 = ???.

I usually copy-paste the

Answer 1

As Andy says, the answer is yes there is a calculator that can understand most latex formulas: Emacs.

Try the following steps (assuming vanilla emacs):

1. Open emacs
2. Open your .tex file (or activate latex-mode)
3. position the point somewhere between the two $$ or e.g. inside the begin/end environment of the formula (or even matrix).
4. use calc embedded mode for maximum awesomeness

So with point in the formula you gave above:

$\frac{154,7}{25} - (289 - \frac{1337}{42})$

press C-x * d to duplicate the formula in the line below and enter calc-embedded mode which should already have activated a latex variant of calc for you. Your buffer now looks like this:

$\frac{154,7}{25} - (289 - \frac{1337}{42})$

$\frac{-37651}{150}$`

Note that the fraction as already been transformed as far as possible. Doing the same again (C-x * d) and pressing c f to convert the fractional into a floating point number yields the following buffer:

$\frac{154,7}{25} - (289 - \frac{1337}{42})$

$\frac{-37651}{150}$

$-251.006666667$

I used C-x * d to duplicate the formula and then enter embedded mode in order to have the intermediate values, however there is also C-x * e which avoids the duplication and simply enters embedded mode for the current formula.

If you are interested you should really have a look at the info page for Emacs Calc - Embedded Mode. And in general the help for the Gnu Emaca Calculator together with the awesome interactive tutorial.