# plotting a polynomial function

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Edited: Walter Roberson on 23 Oct 2023
How can I plot a polynomial function in MATLAB? for example:
89.9659+0.1110371T-0.001472155T^2+ 1.1E-5T^3-4.381E-8T^4+1E-10T^5

Edited: Walter Roberson on 23 Oct 2023
y_1 = @(x) -0.6729+4.8266*x-0.4855*x.^2+0.0312*x.^3
y_1 = function_handle with value:
@(x)-0.6729+4.8266*x-0.4855*x.^2+0.0312*x.^3
x_1 = 0:0.1:33.5;
plot(x_1,y_1(x_1))
##### 3 CommentsShow 1 older commentHide 1 older comment
madhan ravi on 4 Jun 2020
Guck mal hier Breitenbach:
doc colon
Morne' Breitenbach on 5 Jun 2020
Sorry not German or Dutch, my surname is Afrikaanse. so I presume you ment "look here", we write it as "Kyk heir"(said Cake Hirr(like the i in his with a pronounced roll of the r). So the zero means that our number set begins at zero and ends at 33.5, and we get from zero to 33.5 by adding incraments of 0.1? Is this correct?

Rubén Lumbiarres on 13 Sep 2018
Edited: Walter Roberson on 15 Sep 2018
x=-5:.1:5;
p=[1 -1 -11 9 18] % polynomial function
plot(x,polyval(p,x))
grid on
Brian Trease on 24 Nov 2020
Thanks!
I made it one step easier, with no need to specify spacing...
fplot(@(x) polyval(p,x), [-5 5])
grid on

Fangjun Jiang on 14 Dec 2011
Of course ezplot(), but you need to fix your formula.
ezplot('89.9659+0.1110371*T-0.001472155*T^2+ 1.1E-5*T^3-4.381E-8*T^4+1E-10*T^5')
Thanks Fangjun, how can I plot from T=100 to T=1000?
When I use xlim([100 1000]), It doesn't plot in this interval.

Walter Roberson on 14 Dec 2011
Edited: Walter Roberson on 23 Oct 2023
You are asking to plot data that has a range of about 10^10 at one end, and about 10^20 at the other end. What are you expecting to see of interest?
T=linspace(100,1000,100);
p=89.9659+0.1110371*T-0.001472155*T.^2+ 1.1E-5*T.^3-4.381E-8*T.^4+1E-10*T.^5;
plot(T,p)
Walter, do you mean Because of being so great number (10^2 to 10^20 )it's impossible to see in range of 100 to 1000?
in this interval, value of function is between 0.95 to 0.98 .
Fangjun Jiang on 14 Dec 2011
No. Because you have small coefficients, the range of p is not from 10^2 to 10^20. The maximum value of p is around 7e4.
The point is, you can specify any range of T as you want, use linspace() or 100:100:1000, then use array power ".^" not the matrix power "^" to evaluate p, and then you can use plot().

Ch on 4 Sep 2022
x=-5:.1:5;
p=[1 -1 -11 9 18] % polynomial function
p = 1×5
1 -1 -11 9 18
plot(x,polyval(p,x))
grid on

Pink_panther on 23 Oct 2023
%solve1
fplot(@(x)89.9659+0.1110371.*x-0.001472155.*x.^2+1.1E-5.*x.^3-4.381E-8.*x.^4+1E-10.*x.^5)