mathematica-8

I want to interpolate a function in mathematica. The function depends on a parameter a , in fact it is the inverse of a function F which also depends on a , so I build my approximation as follows, approx = Interpolation[Table[{F[0.1 n, a], 0.1 n}, {n, -100, 100}]] now I can simply call approx[x] to evaluate the inverse function at a point. Instead I would like to do something like this: Define a function which takes a parameter, G[x_,a_] = "construct the interpolating function, and return the value of the function at x" Then write G[x,a] to evaluate the function. Otherwise I would have to

The St. Louis Federal Reserve Bank has a great set of data available on a variety of their web pages, such as: http://research.stlouisfed.org/fred2/series/OILPRICE/downloaddata?cid=32217 http://www.federalreserve.gov/releases/h10/summary/default.htm http://research.stlouisfed.org/fred2/series/DGS20 The data sets get updated, some as often as daily. I tend to have an interest in the daily data (see the above settings on the URLS) I'd like to import these kinds of price or rate data streams (accessible as CSV or Excel files at the above URLs) directly into Mathematica. I've looked at the

If you take a look at the Combinatorica package in Mathematica8 in (mathematicapath)/AddOns/LegacyPackages/DiscreteMath/Combinatorica.m you will find the definitions of functions. What I'm interested to know is how Mathematica knows how to format the usage messages. Something tells me that I'm not looking at the right file. In any case, lets try the following: Cofactor::usage = "Cofactor[m, {i, j}] calculates the (i, j)th cofactor of matrix m." This line is the 682 line in the file mentioned above. Now if we run it in a mathematica notebook and we use ?Cofactor we will see the exact same

To the downvoters: this isn't a question about mathematics, it's a question about the programming language Mathematica . One of the prime characteristics of Mathematica is that it can deal with many things symbolically. But if you come to think about it, many of the symbolic features are actually only halfway symbolic. Take vectors for instance. We can have a symbolic vector like {x,y,z}, do a matrix multiplication with a matrix full of symbols and end up with a symbolic result and so we might consider that symbolic vector algebra. But we all know that, right out of the box, Mathematica does

This relates to an earlier question from back in June: Calculating expectation for a custom distribution in Mathematica I have a custom mixed distribution defined using a second custom distribution following along the lines discussed by @Sasha in a number of answers over the past year. Code defining the distributions follows: nDist /: CharacteristicFunction[nDist[a_, b_, m_, s_], t_] := (a b E^(I m t - (s^2 t^2)/2))/((I a + t) (-I b + t)); nDist /: PDF[nDist[a_, b_, m_, s_], x_] := (1/(2*(a + b)))*a* b*(E^(a*(m + (a*s^2)/2 - x))* Erfc[(m + a*s^2 - x)/(Sqrt[2]*s)] + E^(b*(-m + (b*s^2)/2 + x))*