武汉电信dns劫持:matlab如何求解待定系数的问题
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matlab怎么用待定系数法?
如:已知:2*x^3+3*x^2+21*x+4=a*x^3+b*x^2+c*x+d
利用待定系数法可以很容易的得出abcd的值,如何用matlab实现呢?
谢谢
如:已知:2*x^3+3*x^2+21*x+4=a*x^3+b*x^2+c*x+d
利用待定系数法可以很容易的得出abcd的值,如何用matlab实现呢?
谢谢
If all coefficients are numerical, use function: sym2poly()
>> syms x
>> f=2*x^3+3*x^2+21*x+4;
>> sym2poly(f)
ans =
2 3 21 4
If there is any symbolic coefficient, use function: coeffs()
>> syms x a;
>> f=3*a*x^2+2*x^3+21*x+4;
>> [c,l]=coeffs(f,'x')
c =
[ 4, 21, 2, 3*a]
l =
[ 1, x, x^3, x^2]
Function expand() is sometimes useful.
>> syms x a
>> [c l]=coeffs(expand((a+x)^2),'x')
c =
[ a^2, 2*a, 1]
l =
[ 1, x, x^2]