polyfit whats wrong?
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x = [0;0.25;0.5;0.75;1;1.25;1.5;1.75;2;2.25;2.5;2.75;3]
y = [0.652;0.217;0.264;0.0689;-0.183;0.209:0.529;0.689;1.18;1.48;2.21;3.09;3.64;]
p1 = polyfit( x, y, 4)
why isn´t this working?
回答（1 个）
Star Strider
2020-12-21
‘why isn´t this working?’
It should throw an error telling you exactly what the problem is. When I ran the code you posted, the result was:
Error using polyfit (line 44)
The first two inputs must have the same number of elements.
Here, ‘x’ is a (13x1) vector and ‘y’ is a (12x1) vector.
They have to have the same numbers of elements. It appears that an element is missing from ‘y’.
7 个评论
Joao Mendes
2020-12-21
Joao Mendes
2020-12-21
Star Strider
2020-12-21
That works!
If you want to also see the plot:
x = [0;0.25;0.5;0.75;1;1.25;1.5;1.75;2;2.25;2.5;2.75;3];
y = [0.652;0.217;0.264;0.0689;-0.183;0.209; 0.529;0.689;1.18;1.48;2.21;3.09;3.64;];
p1 = polyfit( x, y, 4);
yv = polyval(p1, x);
figure
plot(x, y, 'p')
hold on
plot(x, yv, '-r')
hold off
grid
.
Joao Mendes
2020-12-21
Joao Mendes
2020-12-21
Star Strider
2020-12-21
You have a script that you named ‘polyfit’. That’s the problem.
The solution is to change the name of your script to something like ‘mypolyfit’ or something else that makes sense in the context of whatever you’re doing.
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2020-12-21
2020-12-21
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