Hello.

I need to filter a 2D Matrix based on the values in one of its columns.

Let's have a 2D Matrix like this one:

[1, 2]
[-2, 3]
[3, 18]

Now let's suppose we want to remove all rows with a negative number in the first column (second row in our example).

One possible solution would be to iterate over the whole Matrix in a for-loop removing rows one-by-one, but I was hoping for something more elegant (and hopefully faster).

Hello.

I know that I can use Maple to fit a curve on  data points (Fit command).
However, I'd like to plot (1sig, 2sig, 3sig) confidence contours for the fit parameters.
Is there any way how to do this in Maple 12?

Thanks.

Hello, I am new to Maple (I am used to Mathematica 5.2). I have a differential equation which can be solved numerically (evolution of the scale factor of the Universe containing matter, radiation and dark energy). I've figured out how to use the interactive dsolve() to produce two dimesional plots of R vs. t, yet I'd like to make a nice 3D plot (in cylindrical coordinates) with [R ,R ,t] axes. Having a symbolic solution I would use Mathematica with something like: ParametricPlot3D[{R[t] Cos[x], R[t] Sin[x], t}, {t, -1, 3}, {x, 0, 2Pi}]; In the interactive dsolve() mode Maple offers 3-D plot but it is not what I want...