plot P1 or P2 is right, but I see a wrong in the figure(P1+P2), how to solve it?

asked 2022-03-28 12:40:58 +0100

Anonymous

updated 2022-03-28 16:11:15 +0100

The plots P1 and P2 below are correct, but when I combine them using P1 + P2, there is a break. How to solve it?

sage: t = SR.var('t')
sage: soln1 = lambda t: 196/3 - 196*exp(-3*t/20)/3
sage: P1 = plot(soln1(t), 0, 30, plot_points=1000)
sage: soln2 = lambda t: 1/10470*(102606*e^t + 573835)*e^(-t)
sage: P2 = plot(soln2(t), 30, 50, plot_points=1000)
P1# the figure is right
P2# the figure is also right
P1+P2 # the figure is wrong in the point (t=30)

Comments

You're asking for it ! You plot

P1 between 0 and 29
P2 between 30 and 50

Sage, lacking psychic.py, has no way to divine your intention of having "something" (what ?) plotted between 29 and 30.

What do you mean ?

Emmanuel Charpentier ( 2022-03-28 15:35:00 +0100 )edit

Sorry. I write the wrong question. let me correct it

TimeVector ( 2022-03-28 16:08:28 +0100 )edit

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answered 2022-03-28 17:28:03 +0100

tmonteil
27423 ●31 ●204 ●517 http://wiki.sagemath.o...

I am not sure there is anything wrong in the picture: P2 is the graph of a function that is nearly constant:

sage: soln2(30).n()
9.80000000000513
sage: soln2(40).n()
9.80000000000000
sage: soln2(4000).n()
9.80000000000000

So, when you put it on the same plot as P1, since soln1 ranges from 0 to more than 64, the graph of soln2 looks flat.

sage: soln1(0).n()
0.000000000000000
sage: soln1(30).n()
64.6075455595015

I am not sure of what you are expecting at x=30, but you can join the endpoints of the two plots as follows:

sage: P1 + P2 + line2d([(30,soln1(30)), (30,soln2(30))])

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Comments

you can use P2.show() see figure

TimeVector ( 2022-03-29 07:32:57 +0100 )edit

Oh！ I know it , thanks!

TimeVector ( 2022-03-29 07:36:07 +0100 )edit

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plot P1 or P2 is right, but I see a wrong in the figure(P1+P2), how to solve it?

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plot P1 or P2 is right, but I see a wrong in the figure(P1+P2), how to solve it?