Kata

In this Kata, we use the Euler method for integrating a function (see wiki).

Remember that integrating a function basically means 'calculating the area under a curve'. One way to approximate the area is to chop it up into rectangles (whose area is just height * width) and sum them (see this other wiki page which has a nice gif illustrating this point). We are going to do just this.

Let y = 5 + 2 * x + 3 * x^2.

Write a function

def euler(stop, step_size)

that calculates the integral of y between x = 0 and x = stop. For the sake of simplicity, stop > 0.

As the example test shows, the code will be verified by using a step_size of 0.0001, then rounding the output to the nearest integer.