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| Discussions |
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| Is it possible that you previously assigned a value of 0.4 to t? If so that will be remembered in cache and that can cause the error message that you see. You can use things like Clear or ClearAll or Unset to get Mathematica to remove an item from... |
| Table[{q, f[q]==g[q]},{q, -7 Pi, 7 Pi, 2 Pi}] returns {{-7 Pi,False},{-5 Pi,False},{-3 Pi,False},{-Pi,False},{Pi,False},{3 Pi,False},{5 Pi,False},{7 Pi,False} |
| I run your first block of code and I get the error that you get. But it doesn't really clearly show me why something is not numeric. So I try F[0.999994,1] // InputForm and I get Out[8]//InputForm= -598.2275653440438 -... |
| Your second little grey information box including Sparsearray[ ... {1,1}->{1,1}->20.8 .... shows something is very wrong for you to get {1,1}->{1,1}->20.8 Maybe I broke something in the way I coded that. I apologize. ... |
| Try your example with 1/2 replacing 0.5 |
| I am guessing I still don't have this correct because the plots do not match. If you can find any mistakes that I have made then please point them out. I'm trying to reproduce your very first example. If you can think of any little experiment we... |
| A 3D plot can do tens of thousands, or many more, points and if each of those points requires a very slow calculation then that might partly explain why the plot is so slow. If your function is sufficiently well behaved and the computer has some... |
| If, just before your second Plot, you insert Table[u[x,t],{x,-10,10,5},{t,0,20,5}] to see some of the expression you are trying to plot then you will see that most of it consists of complex numbers, which do not plot. In your... |
| This ToCharacterCode["123abc"] returns {49,50,51,97,98,99} and Fold[256*#1+#2&,0,ToCharacterCode["123abc"]] returns 54091680146019 I got all that by wandering around the help pages with a few lucky guesses. ... |
| See if you can adjust this to get closer to what you want DensityPlot[Sin[x]+1,{x,0,3Pi},{y,0,Pi},ColorFunction->GrayLevel,PlotPoints->100] |