# User Portlet

Discussions |
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How much do you pay me if I do your homework for you? Normally I don't answer copy&paste questions like this, but because I'm bored you're lucky this time. ![solution][1] [1]:... |

"EI" is not defined, as "PA" and "CI" are not defined either. |

tMax = 10; f = Sin[t]; nds = NDSolve[{x'''''[t] == f, x''''[0] == 0, x'''[0] == 0, x''[0] == 0, x'[0] == 0, x[0] == 0}, x, {t, 0, tMax}, MaxSteps -> Infinity, Method -> {"ImplicitRungeKutta", "DifferenceOrder"... |

see [http://reference.wolfram.com/language/ref/D.html][1] Mathematica: y = ?(2+5x); Y = D[y,x]; x =1; Y Wolframalpha: D(sqrt(2+5x),x) [click][2] [1]: http://reference.wolfram.com/language/ref/D.html ... |

This y=Range[...] things looks like you have worked with Matlab before (where it is usual to handle such situations like this) am I right? |

You can also go to [Wolframalpha][1] and enter reduce 29 = a*t & 71 = a/2*t^2 or feed Mathematica with r = Reduce[29 == a*t && 71 == a/2*t^2] N@r[[1]] N@r[[2]] This might be a more comprehensible way. [1]:... |

First I define a simple test animation: p = Manipulate[ Plot[y, {x, 0, 1}, PlotRange -> {{0, 1}, {0, 1}}], {y, 0, 1}] Then I export it to an .avi file, which I later convert into an animated .gif with Photoshop: ... |

You obviously have no definition for f1[] and f2[]. |

Thanks, I didn't know that. I just realized that then it's also possible to have Sqrt''''[x] etc., Problem fixed. |

Manipulate[ f[t_] := E^(-a*t)*Cos[b*t]; g[t_] := E^(-a*t)*Sin[b*t]; c[t_] := {f[t], g[t]}; Grid[{{Show[ ParametricPlot[c[t], {t, 0, B}, PlotStyle -> {Thick, Blue}, PerformanceGoal ->... |