Error in plotting tan

Posted on 2007-02-23 15:17 By zakyn (

96)

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Hello,

I found an error in the following plotting.

An error is with discont=true and the range <-5,5>x<-5,5>

In other cases it is OK.

plot(tan, -5 .. 5, -5 .. 5, discont = true);

But when I plot tan as an expression no as a function it works correctly.

plot(tan(x), x = -5 .. 5, -5 .. 5, discont = true);

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Comments

symbolic versus numeric discontinuities

Comment on 2007-02-23 15:50 from JacquesC ( Maple Rating 4

1699)

I am not 100% sure of this, but I think the issue is one of numeric versus symbolic. More exactly, Maple does symbolic finding of discontinuities for expressions (like tan(x)) via discont and thus powerful commands like limit, series and solve. However, it does numeric finding of discontinuities in the case of procedures (like tan) via the much less powerful fdiscont (purely) numerical routine.

[In this particular case, it would be relatively easy to hack up plot to recognize that this is not an arbitrary function, but a known one. But it would be just that, a hack.]