plotting a polynomial function

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mohammad
mohammad 2011-12-14
编辑： Walter Roberson 2023-10-23
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

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mohammad
mohammad 2012-6-18
编辑：Walter Roberson 2023-10-23
Ran in:
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))
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Morne' Breitenbach
Morne' Breitenbach 2020-6-5
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?

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

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Fangjun Jiang
Fangjun Jiang 2011-12-14
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')
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mohammad
mohammad 2011-12-14
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.

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Walter Roberson
Walter Roberson 2011-12-14
编辑：Walter Roberson 2023-10-23
Ran in:
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)
  2 个评论
mohammad
mohammad 2011-12-14
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
Fangjun Jiang 2011-12-14
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().

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Ch
Ch 2022-9-4
Ran in:
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
Pink_panther 2023-10-23
Ran in:
%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)

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