Design patterns in a mathematical problem

Training of the principles of OOP, SOLID, design patterns on a mathematical project. The program calculates the roots of quadratic equations of different types.

Mathematic

The program solves the following types of quadratic equations:

• complete;
• incomplete;
• biquadrate.

Design patterns

• strategy;
• chain of responsibility;
• singleton;
• facade.

Patterns

Strategy

• ITypeQe — interface. Its subclasses determine how the discriminant or the roots of the equation are calculated;
• ACalcRoots — abstract class. Its subclasses determine how the roots are calculated through the discriminant;
• ACalcQe — abstract class. Its subclasses determine how the roots of the equation are calculated.

Chain of responsibility

The heirs of ACalcQe work with objects of heirs of the same class:

• CalcQeByD counts roots using CalcRootsByD;
• CalcIqe checks the roots of equations using CheckRootsBySubstitution;
• CalcQeByD checks the roots of equations using CheckRootsBySubstitution or CheckRootsByVieta.

Singletone

DefineType defines the type of equation.

Facade

• DefineType hides initialization of objects of type ACalcQe: determines the type of equation by the specified variables and selects a class for calculating the equation;
• CalcQeByD works with objects of other classes to calculate the discriminant, the roots of the equation, and verify the solution;
• CalcIqe works with objects of other classes to calculate the roots of the equation and verify the solution.

How to improve

• Manual input;
• More tests, in particular, of the DefineType class and equation types;
• The principle of openness/closeness in CalcRootsByD, CheckRootsBySubstitution when working with a biquadrate equation;
• ✅ The principle of substitution of Lisks in the heirs of ACalcQe (the problem is in IsRootsCorrect);
• ✅ Checking the roots of all types of equations.

Links:

• https://izamorfix.ru/matematika/algebra/kvadratnye_uravn.html
• https://izamorfix.ru/matematika/algebra/diskriminant.html
• https://izamorfix.ru/matematika/algebra/nepolnye_kv_ur.html
• https://izamorfix.ru/matematika/algebra/teorema_vieta.html
• https://izamorfix.ru/matematika/algebra/bikvadratnye_uravn.html