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Hello. I have been experimenting with springs and masses, and sometimes, when I plot the x of t functions, I get gaps in the plotline. Thickening the line makes no difference; the gaps are still there. Why should this be?
DSolve[{-2*x1[t] + x2[t] == x1''[t], -2*x2[t] + x1[t] == x2''[t],   x1[0] == -1, x2[0] == 2, x1'[0] == 0, x2'[0] == 0}, {x1, x2}, t] produces a short and elegant result but when I extend the syntax to cover three masses and four springs, I get reams...