Roots of Small Degree Polynomials with Real Coefficients by James Pate Williams, BA, BS, MSwE, PhD

We designed and implemented quadratic formula, cubic formula, and quartic formula solvers using the formulas in the Wikipedia articles:

https://en.wikipedia.org/wiki/Quadratic_formula

https://en.wikipedia.org/wiki/Cubic_function

https://en.wikipedia.org/wiki/Quartic_function

We tested our C# implementation against:

https://keisan.casio.com/exec/system/1181809415

http://www.wolframalpha.com/widgets/view.jsp?id=3f4366aeb9c157cf9a30c90693eafc55

https://keisan.casio.com/exec/system/1181809416

Here are screenshots of the C# application:

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C# source code files for the application:

CubicEquation – Copy.cs

IOForm – Copy.cs

MainForm – Copy.cs

QuadraticEquation – Copy.cs

QuarticEquation – Copy.cs

A Simple and Utilitarian C# Matrix Class by James Pate Williams, BA, BS, MSwE, PhD

We designed and implemented a simple and utilitarian C# matrix class for double precision numbers. The class has the binary matrix operators +, -, *, / which are addition, subtraction, multiplication, and division of two matrices. We also include an operator for multiplication of matrix by a scalar and an operator for dividing a matrix by a scalar. We have included functions to compute the p-norm, p, q-norm, and max norm of a matrix. We also can calculate using truncated infinite series the exponential, cosine, and sine function of a matrix. The exponential and trigonometric functions use a powering function that raises a matrix to a non-negative integral power.

Below is a screenshot of the test Windows Forms application. We execute the four binary matrix operators in the order +, -, *, / e.g. A+B, A-B, A*B, A/B. In order to divide by B, the matrix B must be square and non-singular, that is square and invertible.

Matrix Example Application Screenshot

The B matrix has the form of the matrix in the online discussion:

http://www.purplemath.com/modules/mtrxinvr2.htm

We create a project named MatrixExample. In this project we add a Matrix class whose code is given below:

Matrix

I leave it as an exercise for the reader to test the various norms and other functions.