Evaluating a function at complex values
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I am new to MATLAB and I am trying to evaluate a sybomlically defined function at complex values, but I get an error saying 'Array indices must be positive integers or logical values'. What should I change so that this works and outputs a complex value?
syms x
F = x^5-5*x^4-8*x^3+40*x^2-9*x+45;
P0 = 0+1i;
F(P0)
采纳的回答
Ameer Hamza
2020-11-4
F is a symbolic expression, not a symbolic function. You need to use subs()
syms x
F = x^5-5*x^4-8*x^3+40*x^2-9*x+45;
P0 = 0+1i;
subs(F, x, P0)
Following define F as symbolic function
syms x
F(x) = x^5-5*x^4-8*x^3+40*x^2-9*x+45;
P0 = 0+1i;
F(P0)
更多回答（1 个）
Alan Stevens
2020-11-4
编辑：Alan Stevens
2020-11-4
You need to make sure F is a function. For your particular function you don't need it to be symbolic:
>> F =@(x) x^5-5*x^4-8*x^3+40*x^2-9*x+45;
>> P0 = 2+0.5*i;
>> F(P0)
ans =
87.3125 -11.4688i
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