Dynamic problem (possibly simple)

*To*: mathgroup at smc.vnet.net*Subject*: [mg92889] Dynamic problem (possibly simple)*From*: "m.g." <mg at michaelgamer.de>*Date*: Fri, 17 Oct 2008 05:22:44 -0400 (EDT)

Hi all, I have the following problem: I want to dynamically plot a function (tangential plane to a 3D Plot) One part is that I have to compute the gradient of the function. I could not manage this (dynamically). I have stripped of any unnessesary code to descripe the problem, so look at this: This makes a slider to select a point (works well, of course) {Slider2D[Dynamic[aufpunkt], {{-2, -2}, {2, 2}}], Dynamic[aufpunkt]} This should do a computation with "aufpunkt" (does not work) DynamicModule[{x, y, a, b}, x = Dynamic[aufpunkt[[1]]]; y = Dynamic[aufpunkt[[2]]]; y^2 ] The output is not evaluated, I get, for instance, (0.5)^2, instead of 0.25. How can I manage to get the formula (y^2 in this case) evaluatet? Greetings Mike