Implement integral, indefinite integral. #30
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| def integral(self, a, b): | ||
| """Return the integral of self from a to b.""" | ||
| res = self.indefinite_integral | ||
| # Last term of indefinite integral is C. | ||
| res[0] = 0 | ||
| return res.calculate(b) - res.calculate(a) | ||
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| @property | ||
| def indefinite_integral(self): | ||
| """Return the polynomial object which is the integral of self.""" | ||
| if not self: | ||
| return Polynomial("C") | ||
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| return Polynomial( | ||
| [c/x for c, x in | ||
| zip(self, range(self.degree + 1, 0, -1))] + ["C"] | ||
| ) | ||
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I suggest adding a parameter for the value of the integration constant, since having the string "C" prevents the polynomial from being very useful for almost all operations and is maybe a not-so-desired result, as opposed to a plain 0 for example. Maybe having the parameter like constant="C" would cover that case, also there would be no need of lines 149 and 150 then.
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How would you cover the case of double integrals? Would we make constants a seperate polynomial that goes at the end?
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Well, currently we haven't implemented anything allowing operations between string and number coefficients, which would be needed for applying indefinite_integral to a polynomial ending with "C". So three options come in my head in this scenario:
- throwing an error (current)
or - implementing something like
nth_integralwhich returns two things: the result without the constants and a polynomial with the constants
or - implementing a class
Integralwhich handles this and can have a polynomial be easily extracted from it
2 participants
This implements integral, which takes a start and end point as arguments and returns the area of the polynomial over the specified range, and indefinite_integral, which returns the indefinite integral of the polynomial.