#22 Statistical distributions (normal, chi-squared...)
Qalculate! should implement statistical cumulative distribution functions such as normal, chi-squared, Student t, and F-distribution, and their inverse counterparts.
For example, normdist(x; 0; 1) would be the normal distribution with mean 0 and std.dev. 1, which is 0 at x=-inf, 0.5 at x=0, and 1 at x=inf. norminv(x; 0; 1) would be the inverse (-inf at x=0; 0 at x=0.5; inf at x=1). Additionally, there could be a normdens(x; 0; 1) function with the density function (which is 0 at x=-inf, grows to a maximum of approx. 0.399 at x=0, and then shrinks back to 0 at x=inf).
(Note that this doesn't have to do with statistical analysis of a set of data, nor with generation of random numbers with a certain distribution; these are functions f:R->R used in statistics)
http://en.wikipedia.org/wiki/Normal_distribution
http://en.wikipedia.org/wiki/Chi-squared_distribution
http://en.wikipedia.org/wiki/Student%27s_t-distribution
http://en.wikipedia.org/wiki/F-distribution