Error using feval Function to evaluate must be represented as a string scalar, character vector, or function_handle object.
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f(t)=[-cos(t), -sin(t), 2*cos(t)^3 - 7*cos(t)*sin(t)^2]
feval(f(t),3.14)
I'd like to evaluate the vector value function above at 3.14, but I get the error message in the subject line. How do I fix this?
采纳的回答
Another approach, if you don't want to work symbolically as @Walter Roberson did, is to create an anonymous function. All I needed to do was move the equals sign and add an @ symbol.
f = @(t) [-cos(t), -sin(t), 2*cos(t)^3 - 7*cos(t)*sin(t)^2]
feval(f,3.14)
But with an anonymous function you don't even need feval.
y = f(3.14)
Given what you're doing the pi function may be of interest to you, as may the cospi and sinpi functions.
更多回答（1 个）
syms t
f(t)=[-cos(t), -sin(t), 2*cos(t)^3 - 7*cos(t)*sin(t)^2]
Then
output = feval(f,3.14) %must "use" the output
or
f(3.14) %do not need to "use" the output
or
subs(f(t), t, 3.14) %do not need to "use" the output
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