Creating a symbolic variable, then using it as a real variable
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I need my program to calculate the derivative of a function, and as far as I understand that means I need to make a symbolic variable. How then can I continue to use that variable as a real vector?
This is what I have tried:
syms x
y = input('Please enter a valid function of x')
deriv = diff(y)
syms clear
x = 0:pi/30:pi;
plot(x,y)
采纳的回答
syms x
y = input('Please enter a valid function of x: ')
deriv = diff(y) % This will be symbolic
x = 0:pi/30:pi; % Now x is a double.
y = matlabFunction(y) % y is a function handle.
plot(x,y(x))
2 个评论
Tom
2012-10-25
y is a function handle (as I say in the comment!), not a vector. If you want to make y a vector instead:
syms x
y = input('Please enter a valid function of x: ')
x = 0:pi/30:pi; % Now x is a double.
y = subs(y); % y is now a double.
plot(x,y)
Or without the symbolic toolbox at all:
x = 0:pi/30:pi;
y = 'Please enter a valid function of x: ';
y = feval(vectorize(inline(input(y,'s'))),x);
plot(x,y)
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