how to get function value?

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Ani Asoyan
Ani Asoyan 2020-6-3
评论： Ani Asoyan 2020-6-3
Hi I want to evaluate function and its derivative at a=2 , how to do that?
syms a
b=2
e=0.9
q=1.2
g=2
k=3
d=0.5
f=(q*b*e/a-d*e)/((q^2)*(e^2)/a+2*e*g)
diff(f)

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采纳的回答

madhan ravi
madhan ravi 2020-6-3
df(a) = diff(f)
df(2)
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madhan ravi
madhan ravi 2020-6-3
编辑：madhan ravi 2020-6-3
P.S: You have some troubles with copying.
f(a) = (q*b*e/a-d*e)/((q^2)*(e^2)/a+2*e*g)
f(2)
Ani Asoyan
Ani Asoyan 2020-6-3
oh I'm so bad at matlab :D .. thank you

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更多回答（1 个）

David Hill
David Hill 2020-6-3
syms a;
b=2;
e=0.9;
q=1.2;
g=2;
k=3;
d=0.5;
f=(q*b*e/a-d*e)/((q^2)*(e^2)/a+2*e*g);
df=diff(f);
fvals=eval(subs(f,1:10));%evaluate f from 1:10 (if you want actual symetric value eleminate the eval function
dfvals=eval(subs(df,1:10));
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madhan ravi
madhan ravi 2020-6-3
Nah using eval(...) is o]absolutely not needed here! forget it!
Ani Asoyan
Ani Asoyan 2020-6-3
I agree,, David Hill , thanks for the effort, but I think I'll go with the other answer, sorry

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