Ok, this mut have been asked a million times, but for the heck I cannot find how to do it:

I have a data file with many columns of data, delimiited, and many rows. I can read this in with ImportMatrix no sweat. The generated matrix has (row,column) format, i.e. matrix[1] is row 1 etc.

Now I want to plot two arbitrary columns against each other, say matrix[][19] vs matrix[][13] (the 19th column vs the 13. column). The data are monotonic in each vector so I can...

I have a calculation (analytic) involving sums (finite) that ends up with an expression structured like a sum over an expression with several terms, like

sum(Y(t)*cos(omega*t) + a*sin(omega*t)+b*cos(omega*t),t);

(The real case is more involved but this simple example shows the issue.)

What I want is to distribute the sum over each term separately, observing that a & b are numbers & therefore can be pulled out of the sum. Note that the expression...