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- #!/usr/bin/ruby
- # Numerical approximation of the derivative of a function `f(x)`, at a given value `x`.
- # Formula:
- # f'(x) = Limit_{h -> 0} (f(x + h) - f(x))/h
- # See also:
- # https://en.wikipedia.org/wiki/Derivative
- # https://en.wikipedia.org/wiki/Numerical_differentiation
- func derivative(f, x, h=1e-49) {
- (f(x + h) - f(x)) / h
- }
- # Example for: f(x) = x^3 + x^2
- # where: f'(x) = 3*x^2 + 2*x
- say derivative({|x| x**3 + x**2 }, 10) #=> 320
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