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 Author Comment/Response Deanne Taylor 12/03/00 3:16pm Hi! I'm having a problem in Mathematica, once which is very vexing and I'm not sure what I need to do to fix it. Basically, I am calculating several variables that themselves depend on one symbolic variable, like so: x(y,t)=const1*y(var1)*Cos[t*const2] where const1 and 2 are just constants, and y is a function of ''var1'', another variable. In Mathematica, after declaring y=const1 * var1 x=const2*y*Cos[const3*t] I want to graph x in Plot3D, such as, Plot3D[x,{var1,0,ymax},{t,0,tmax}] where ymax and tmax are already defined. So, basically, y is parameterized, I guess, for var1. Unfortunately, I get error messages thus: '' Plot3D::''plnc'': x is neither a machine-size real number at{y, t}={0.1694915254237288, 0.`} nor a list of a real number and a valid color directive.'' My function IS evaluating correctly; when I substitute y and t for numbers, I get expressions that are purely numeric. The interesting thing is this: When I re-define x in terms of var1 explicitly by substituting y's function for y, of course Plot3D works! So something like x=(const1 * var1)*const2 * Cos[const3*t] will work with Plot3D as I've typed it above. Basically, I see this as a persistence problem...the Plot3D does not understand that y's variable var1 must be ''brought through'' with the x(y,t) so that x is really x(var1,t) in order to plot it. I need it to remain thusly because of the complexity of the previous notebook expressions. Can anyone help me figure out how to make x a function of y's 'var1' explicitly without typing in all of y every time? The problem is that y changes depending on what it is a function of, and I want to be able to graph x no matter what single variable I am deciding to vary in y. URL: ,

 Subject (listing for 'Persistence in Functions...none?') Author Date Posted Persistence in Functions...none? Deanne Taylor 12/03/00 3:16pm Re: Persistence in Functions...none? Forum Modera... 12/04/00 05:23am
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