How to plot polynomial function correctly?

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Adrian Brand
Adrian Brand 2020-3-24
评论： María Guadalupe Gama Cruz 2021-2-24
Hello, I'm trying to plot polynomial function but output is always bad. Can you help me find, what I'm missing? Thank you.
This is my code:
d = @(g)1-5*g-2.5*g.^2+6*g.^3+5*g.^4;
e = -2:1/100:2;
plot(e,d(e));
This is what I'm getting:
And this is what I want:

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采纳的回答

Alex Mcaulley
Alex Mcaulley 2020-3-24
Your code is working fine, the difference is just the axis limits. Try this:
d = @(g)1-5*g-2.5*g.^2+6*g.^3+5*g.^4;
e = -2:1/100:2;
plot(e,d(e));
ylim([-2,5])
xlim([-3,6])

更多回答（1 个）

John D'Errico
John D'Errico 2020-3-24
编辑：John D'Errico 2020-3-24
Hmm. Why does this feel like deja vu? (Answer: I just answered almost the same question for someone else, not 5 minutes ago.)
d = @(g)1-5*g-2.5*g.^2+6*g.^3+5*g.^4;
e = -2:1/100:2;
plot(e,d(e));
grid on
It looks fine to me. Whats the problem? That two programs arbitrarily chose a different set of axes to plot the same curve?
axis([-3,4.5,-1.5,4.5])
Same curve. Same plot. Very different conclusions, just by changing the axis scaling.

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