Computer Lecture 7

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POLYNOMIALS IN MATLAB
A polynomial of degree ???1 has the form:
(??)=????????+?????1?????1+?+??1??+??0,
where the ??????? are constants and ?????0.

Examples: the following are polynomials:
3x+5
x^2-2x+3
2x^3+x^2-4x+6
2x^4-x^2+5
To enter the polynomials above in MATLAB, we enter
>> p1=[3 5]
>> p2=[1 -2 3]
>> p3=[2 1 -4 6]
>> p4=[2 0 -1 0 5]
sym2poly and poly2sym

There are built-in functions sym2poly and poly2sym that convert from symbolic expressions to polynomial vectors and vice versa, for example:
>> s1= poly2sym(p1)
s1=
3*x+5

>> s2= poly2sym(p2)
s2=
x^2-2*x+3

>> s3= poly2sym(p3)
s3=
2*x^3+x^2-4*x+6

>> s4= poly2sym(p4)
s4=
2*x^4 – x^2+5

>> sym2poly (s1)
ans=
3 5

>> sym2poly (s2)
ans=
1 -2 3

>> sym2poly (s3)
ans=
2 1 -4 6

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