MATLAB: How Can I define a Polynomial of degree n with symbolic coefficients

polynomialsymbolic coefficients

Hi guys, How can I define a polynomial of degree n with symbolic coefficients. For example, if n=2, P= ax*2+bx+c

Thanks

Best Answer

Whats the problem? This seems clear.

syms x a b c
P = a*x^2+b*x+c;

Are you looking for a general solution for any n? This seems to work:

n = 3;
syms x
P = sym('a',[1,n+1])*x.^(n:-1:0).'
P = 
  a1*x^3 + a2*x^2 + a3*x + a4

Related Solutions

MATLAB: How to make polynom with unknown coefficients

n = 10;
c = sym('c', [1 n]);
p = poly2sym(c)

MATLAB: How to plot a cubic spline from the coefficients

Hi,

In my understanding you have the coefficients of the cubic spline fitted for a graph. For converting the cubic spline coefficient into Horner nested polynomial representation you may try using horner. Below code may help plotting one of the cubic spline you may have. You may plot all spline with appropriate coefficients.

syms x 
% Some random coefficient 
a = rand(10,1); 
b = rand(10,1); 
c = rand(10,1); 
d = rand(10,1); 
p = a(1)*x^3 + b(1)*x^2 + c(1)*x + d(1);  
horner_p = horner(p);  
% Range for each spline to be plotted 
range_to_plot = -10:0; 
fplot(horner_p,[range_to_plot(1),range_to_plot(2)]); 
hold on  
for i = 2:size(a,1)  
    p = a(i)*x^3 + b(i)*x^2 + c(i)*x + d(i);  
    horner_p = horner(p);  
    fplot(horner_p,[range_to_plot(i),range_to_plot(i+1)]);  
end  
hold off

Best Answer

Related Solutions

MATLAB: How to make polynom with unknown coefficients

MATLAB: How to plot a cubic spline from the coefficients

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