Last lab, we learned how to calculate limits. Basically we started by invoking the symbolic toolbox
>>syms x
and then defined a corresponding function f that depends on x. For example to create a function f(x) = x^3 we typed
>>f = x.^3
Now, if we want to calculate the derivative of this function at a symbolic point a, we can do this by using the Matlab command limit:
>>syms a
>>fpa = limit((subs(f,x,x)-subs(f,x,a))/(x-a), x,a)
fpa =
3*a^2
produces the derivative of f(x) at the point a as being 3a^2.
You can also calculate the derivative using the Matlab command diff. For instance,
>>dfdx = diff(2*x+x^4)
ans =
2+4*x^3
will create a function dfdx that contains the derivative 2 + 4x^3. Enjoy!
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