memoize function to avoid repeat of function evaluation

I am using memoize function to avoid repeat of function evaluation in a very computationally expensive optimization problem. But I found that my function is not using the value saved as the inputs are slightly difference by 0.1 or 1%. Is there a way that I can used the previously computed function value if the inputs are within a certain range? example: suppose : I had 6 = f(1) , then I don't want to compute f(1.01). I want to use f(1.01) equal to 6. I want to set that if 0.99 <input <1.01 then use the value f(1) rather than computing again.

Answer 1

[Matt J]

Pre-apply round() or discretize() to the input.