Wha'ts wrong with this?
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I'm very new and I can't detect what's wrong here. I would be very pleased if you could help me. Thanks!
syms x
f(x)=sin(x+1)*sqrt(x+1)
sym(polyfit([1,2,3,4],[f(1),f(2),f(3),f(4)],3))
Inputs must be floats, namely single or double.
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Accepted Answer
Alan Stevens
on 28 Nov 2020
Try
f = @(x) sin(x+1)*sqrt(x+1);
p = polyfit([1,2,3,4],[f(1),f(2),f(3),f(4)],3);
x = 1:0.01:4;
y = polyval(p,x);
plot([1,2,3,4],[f(1),f(2),f(3),f(4)],'o',x,y)
3 Comments
Image Analyst
on 28 Nov 2020
Then can you please "Accept this answer" to give Alan reputation points to thank him for helping you. You can also click the Vote icons to vote for answers and award them additional reputation points.
More Answers (1)
Image Analyst
on 28 Nov 2020
Like it says, x must be a double, not a sym. f is a sym since x was (I'm guessing since I don't have the Symbolic Toolbox.) So just don't define a at all, and don't put polyfit() into sym() either.
3 Comments
Image Analyst
on 28 Nov 2020
Fine, but do it numerically, not symbolically, like Alan and I told you.
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