HP 15c Collector's Edition User Manual

154 Section 12: Calculating with Matrices
Keystrokes Display
-
C 2 3
Calculates B − A and stores
values in redimensioned
result matrix C.
The result is C = 
0 1 2
3 4 8

Matrix Multiplication
With matrix description in both the X- and Y-registers, you can calculate
three different matrix products. The table below shows the results of the
three functions for a matrix X specified in the X-register and a matrix Y
specified in the Y-register. The matrix X
−1
is the inverse of X, and the
matrix Y
T
is the transpose of Y.
Pressing Calculates
*
* YX
´ > 5 Y
T
X
÷ X
−1
Y
*
Result is stored in result matrix. For ÷
, the result
matrix can be Y but not X
. For the others, the result
matrix must be other than X or Y.
Note: When you use the ÷ function to evaluate the expression
A
−1
B, you must enter the matrix descriptors in the order B, A
rather than in the order that they appear in the expression.
*
The value stored in each element of the result matrix is determined
according to the usual rules of matrix multiplication.
For > 5, the matrix specified in the Y-register isn’t changed by this
operation, even though its transpose is used. The result is identical to that
obtained using > 4 (transpose) and *.
*
This is the same order you would use if you were entering b and a for evaluating
a
−1
b = b/ a.

HP 15c Collector's Edition Specifications

General

Model	HP 15c Collector's Edition
Category	Calculator
Type	Scientific
Power Source	Battery
Manufacturer	HP
Display	LCD
Functions	complex numbers, matrix operations

Summary

Introduction

This Handbook

Outlines the structure of the manual, detailing its parts and how to use it for learning.

The HP Community

Discusses user groups and websites for HP calculator enthusiasts and information sharing.

Part I: HP 15c Fundamentals

Section 1: Getting Started

Covers basic operations like powering on, keyboard layout, and primary/alternate functions.

Section 2: Numeric Functions

Explains essential numeric operations including logs, trig, powers, and conversions.

Section 3: The Automatic Memory Stack, LAST X, and Data Storage

Details the RPN stack, LAST X register, and data storage operations.

Part II: HP 15c Programming

Section 6: Programming Basics

Introduces core programming concepts: creating, loading, running programs, and memory.

Section 8: Program Branching and Controls

Covers controlling program flow using branching, loops, and conditional tests.

Part III: HP 15c Advanced Functions

Section 11: Calculating With Complex Numbers

Covers entering, manipulating, and performing calculations with complex numbers.

Section 12: Calculating With Matrices

Explains matrix operations, including dimensioning, element access, and calculations.

Section 13: Finding the Roots of an Equation

Details using the SOLVE function for numerical root finding and equation solving.

Section 14: Numerical Integration

Explains how to perform numerical integration using the ∫f(x)dx key and subroutines.

Appendix A: Error Conditions

Error 8: No Root

Explains the error when the SOLVE function cannot find a root.

Error 0: Improper Mathematics Operation

Lists and explains errors related to mathematical operations and illegal arguments.

Appendix D: A Detailed Look at SOLVE

How SOLVE Works

Explains the numerical technique and logic behind the SOLVE algorithm.

Finding Several Roots

Discusses methods for finding multiple roots of an equation using the SOLVE function.