Matrix Multiplication Calculator NZ

This calculator multiplies two 2 by 2 matrices and shows the resulting product matrix. Matrix multiplication is one of the central operations in linear algebra, and it works quite differently from multiplying ordinary numbers. To find each entry of the product, you take a row of the first matrix and a column of the second, multiply their corresponding elements, and add the results, a row-by-column dot product. This rule, while a little involved, is what makes matrices so powerful: multiplying matrices composes transformations, so a single product can represent rotating then scaling then translating in computer graphics, or chaining the steps of a process. Matrix multiplication underlies graphics and game engines, the linear layers of neural networks, systems of equations, and much of physics and engineering. This tool removes the arithmetic. You enter the four entries of the first matrix and the four of the second, and the calculator returns the product matrix and each of its four entries individually. The results update as you type, so you can explore how the product changes. Use it for linear algebra homework, for graphics and transformation work, or to check a hand calculation. A crucial property the calculator illustrates is that matrix multiplication does not commute: multiplying A by B generally gives a different result from B by A, unlike ordinary numbers, because the order in which transformations are applied matters. Each entry of the product comes from one row of the first matrix and one column of the second: the top-left entry uses the first row and first column, the top-right uses the first row and second column, and so on. The calculations are exact for the values you enter.

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[19 22; 43 50]
product matrix A x B
Top-left19
Top-right22
Bottom-left43
Bottom-right50

Matrix A = [a b; c d], B = [e f; g h]. Each product entry is a row of A times a column of B. Matrix multiplication does not commute: A x B is generally not B x A.

How it works

Each entry of the product is found by taking a row of the first matrix and a column of the second, multiplying corresponding elements and adding. The top-left entry is the first row of A times the first column of B, the top-right uses the first row and second column, and the bottom row uses the second row of A with each column of B.

Worked example

For A = [1 2; 3 4] and B = [5 6; 7 8], the top-left entry is 1 times 5 plus 2 times 7, which is 19. The top-right is 1 times 6 plus 2 times 8, which is 22. The bottom row gives 3 times 5 plus 4 times 7, which is 43, and 3 times 6 plus 4 times 8, which is 50. So the product is [19 22; 43 50].

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