polyfit whats wrong?

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?

Answer 1

[Star Strider]

‘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’.

[Joao Mendes]

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)

what about now?

[Joao Mendes]

it doesn´t say, or I can´t find it

Im using matlab online

[Star Strider]

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]

Thanks for the help!

it does work on my friends matlab but on my own it doesn´t :)

[Jan]

Who doesn' say what? For me the command is working now.

[Joao Mendes]

on my computer it says:

Attempt to execute SCRIPT polyfit as a function:

/MATLAB Drive/polyfit.m

on my friend´s, with exactly the same code it works

[Star Strider]

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.