Appendix A: Glossary
absolute value — The value of a quantity expressed as a positive number, for example, |f(x)|.
accuracy — The degree of exactness provided by a description or theory. Accuracy usually refers to an absolute quality, while precision usually refers to the number of digits used to represent a number.
address — The numerical designation of a location in memory. An identifier, such as a label, that points to an address in memory or a data source.
algorithm — Aset of rules for solving a problem in a finite number of steps. Usually independent of the software or hardware.
allocate — To assign a resource for use, often memory. alphanumeric — The combination of alphabetic letters, numerical digits, and special characters, such as %, $, and /.
analog — The mapping of a continuous physical observable to numbers, for example, a car’s speed to the numbers on its speedometer.
animation—A process in which motion is simulated by presenting a series of slightly different pictures (frames) in succession.
append — To add on, especially at the end of an object or word.
application — A self-contained, executable program containing tasks to be performed by a computer, usually for a practical purpose.
architecture — The overall design of a computer in terms of its major components: memory, processor, I/O, and communication.
archive — To copy programs and data to an auxiliary medium or file system for long-term, compact storage.
argument—A parameter passed from one program part to another or to a command.
arithmetic unit — The part of the central processing unit that performs arithmetic.
array (matrix) — A group of numbers stored together in rows and columns that may be referenced by one or more subscripts. Each number in an array is an
array element. assignment statement — A command that sets a value to a variable or symbol. B — The abbreviation for byte (8 bits). b — The abbreviation for bit (binary digit). background — (1)Atechnique of having a programming run at low priority (“in the
background”) while a higher-priority program runs “in the foreground.” (2) The part of a video display not containing windows.
base — The radix of a number system. (For example, 10 is the radix of the decimal system.)
basic machine language — Instructions telling the hardware to do basic a operation such as store or add binary numbers.
batch — The running of programs without user interaction, often in the background.
baud — The number of signal elements per unit time, often 1 bit per second.
binary — Related to the number system with base 2.
BIOS — Basic input/output system.
bit — Contraction of “binary digit”; digit 0 or 1 in binary representation.
Boolean algebra — A branch of symbolic logic dealing with logical relations as opposed to numerical values.
boot — To “bootstrap”; to start a computer by loading the operating system.
branch — To pick a path within a program based on the values of variables.
bug — A mistake in a computer program or operating system; a malfunction.
bus — A communication channel (a bunch of wires) used for transmitting information quickly among computer parts.
byte — Eight bits of storage. Java uses two bytes to store a single character in extended unicode.
byte code — Compiled code read by all computer systems but still needing to be interpreted (or recompiled); contained in a class file.
cache — Small, very fast memory used as temporary storage between very fast CPU registers and main memory or between disk and RAM.
calling sequence — The data and setup needed to call a method or subprogram.
central processing unit (CPU) — The part of a computer that accepts and acts on instructions; where calculations are done and communications controlled.
checkpoint — A statement within a program that stops normal execution and provides output to assist in debugging.
checksum — The summation of digits or bits used to check the integrity of data.
child — An object created by a parent object.
class — (1) A group of objects or methods having a common characteristic. (2) A collection of data types and associated methods. (3) An instance of an object. (4) The byte code version of a Java program.
clock — Electronics that generate periodic signals to control execution.
code — A program or the writing of a program (often compiled).
column — The vertical line of numbers in an array.
column-major order — The method used by Fortran to store matrices in which the leftmost subscript attains its maximum value before the subscript to the right is incremented. (Java and C use row-major order.)
command — A computer instruction; a control signal.
command key —Akeyboard key, or combination of keys, that performsa predefined function.
compilation — The translation of a program written in a high-level language to (more) basic language.
compiler — A program that translates source code from a high-level computer language to more basic machine language.
concatenate — To join together two or more strings head to tail. concurrent processing —The same as parallel processing; the simultaneous execution of several related instructions.
conditional statement — A statement executed only under certain conditions.
control character — A character that modifies or controls the running of a program (e.g., control + c).
control statement — A statement within a program that transfers control to another section of the program.
copy — To transfer data without removing the original.
CPU — See central processing unit. crash — The abnormal termination of a program or a piece of hardware.
cycle time (clock speed) — The time needed for a CPU to execute a simple instruction.
data — Information stored in numerical form; plural of datum.
data dependence — Occurs when two statements are addressing identical storage locations.
dependence — Relation among program statements in which the results depend on the order in which the statements are executed.
data type — Definitions that permit proper interpretation of a character string.
debug — To detect, locate, and remove mistakes in software or hardware.
default — The assumption made when no specific directive is given.
delete — To remove and leave no record. DFT — Discrete Fourier transform.
digital — The representation of quantities in discrete form; contrast analog.
dimension of an array The number of elements that may be referenced by an array index. The logical dimension is the largest value actually used by the program.
directory — A collection of files given their own name.
discrete — Related to distinct elements.
disk, disc — A circular magnetic medium used for storage.
double precision — The use of two memory words to store a number.
download — To transfer data from a remote computer to a local computer.
DRAM — See dynamic RAM. Contrast with SRAM.
driver —Aset of instructions needed to transmit data to or from an external device.
dump — Data resulting from the listing of all information in memory.
dynamic RAM — Computer memory needing frequent refreshment.
E — A symbol for “exponent.” To illustrate, 1.97E2 = 1.97 ×102.
element — An item of data within an array; a component of a language.
enable — To make a computer part operative.
ethernet — A high-speed local area network (LAN) composed of specific cable technology and communication protocols.
executable program — A set of instructions that can be loaded into a computer’s memory and executed.
executable statement — A statement that causes a certain computational action, such as assigning a value to a variable.
fetch — To locate and retrieve information from storage.
FFT — Fast Fourier transform. flash memory — Memory that does not require power to retain its contents.
floating point — The finite storage of numbers in scientific notation.
FLOP — Floating-point operations per second.
foreground — Running high-priority programs before lower-priority programs.
Fortran — Acronym for for mula translation; a classic language.
fragmentation — File storage in many small, dispersed pieces.
garbage — Meaningless numbers, usually the result of error or improper definition. Obsolete data in memory waiting to be removed (“collected”).
giga, G — Prefix indicating 1 billion, 109, of something (US).
GUI — Graphical user interface; a windows environment.
hard disk — A circular, spinning, storage device using magnetic memory.
hardware — The physical components of a computer system.
hashing — A transformation that converts keystrokes to data values.
heuristic — A trial-and-error approach to problem solving.
hexadecimal — Base 16; {0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F}.
hidden line surface — The part of a graphics object normally hidden from view.
high-level language — A programming language similar to normal language.
host computer — A central or remote computer serving other computers.
HPC — High-performance computing.
HTML — Hypertext markup language.
icon — A small on-screen symbol that activates an application.
increment — The amount added to a variable, especially an array index.
index — The symbol used to locate a variable in an array; the subscript.
infinite loop — The endless repetition of a set of instructions.
input — The introduction of data from an external device into main storage.
instructions — Commands to the hardware to do basic things.
instruction stack — The ordered group of instructions currently in use.
interpolation — Finding values between known values.
interpreter — A language translator that sequentially converts each line of source code to machine code and immediately executes each line.
interrupt — A command that stops the execution of a program when an abnormal condition is encountered.
iterate — To repeat a series of steps automatically. jump — A departure from the linear processing of code; branch, transfer.
just-in-time compiler — A program that recompiles a Java class file into more efficient machine code.
kernel — The inner or central part of a large program or of an operating system that is not modified (much) when run on different computers.
kill — To delete or stop a process.
kilo, k — Prefix indicating 1 thousand, 103.
LAN — Local area network.
LAPACK — A linear algebra package (a subroutine library).
language — Rules, representations, and conventions used to communicate information.
LHS — Left-hand side.
library (lib) — A collection of programs or methods usually on a related topic.
linking — Connecting separate pieces of code to form an executable program.
literal — A symbol that defines itself, such as the letter A.
load — To read information into a computer’s memory.
load module — A program that is loaded into memory and run immediately.
log in (on) — To sign onto a computer; to begin a session.
loop — A set of instructions executed repeatedly as long as some condition is met.
low-level language — Machine-related commands not for humans.
machine language — Commands understood by computer hardware.
machine precision—Themaximumpositivenumberthat,when added to the number stored as 1, does not change it.
macro — A single higher-level statement resulting in several lower-level ones.
main method — The section of an application program where execution begins.
main storage — The fast electronic memory; physical memory.
mantissa — Significant digits in a floating-point number; for example, 1.2 in 1.2E3.
mega, M — A prefix denoting a million, or 1,048,576 = 220.
method — A subroutine used to calculate a function or manipulate data.
MIMD — Multiple-instruction, multiple-data computer.
modular programming — The technique of writing programs with many reusable independent parts.
modulo (mod) — A function that yields a remainder after the division of numbers.
multiprocessors — Computers with more than one processor.
multitasking — The system by which several jobs reside in a computer’s memory simultaneously; they may run in parallel or sequentially.
NAN — Not a number; a computer error message.
nesting — Embedding a group of statements within another group.
object — A software component with multiple parts or properties.
object-oriented programming — Amodular programming style focused on classes of data objects and associated methods to interact with the objects.
object program (code) — A program in basic machine language produced by compiling a high-level language.
octal — Base 8; easy to convert to or from binary.
ODE — Ordinary differential equation.
1-D — One-dimensional.
operating system (OS) — The program that controls a computer and runs applications, processes I/O, and shells.
OOP — Object-oriented programming.
optimization — The modification of a program to make it run more quickly.
overflow — The result of trying to store too large a number.
package — A collection of related programs or classes.
page — A segment of memory that is read as a single block.
parallel (concurrent) processing — Simultaneous or independent processing in different CPUs.
parallelization — Rewriting an existing program to run in parallel.
partition — The section of memory assigned to a program during its execution.
PC — Personal computer.
PDE — Partial differential equation.
physical memory — The fast electronic memory of a computer; main memory; contrast with virtual memory.
physical record — The physical unit of data for input or output that may contain a number of logical records.
pipeline (segmented) arithmetic units — An assembly-line approach to central processing; the CPU simultaneously gathers, stores, and processes data.
pixel — A picture element; a dot on the screen. See also voxel.
Portable Document Format, .pdf — A document format developed by Adobe that is of high quality and readable by an extended browser.
PostScript, .ps—Alanguage developed byAdobe for printing high-quality text and graphics.
precision — The degree of exactness with which a quantity is presented. High-precision numbers are not necessarily accurate.
program — A set of instructions that a computer interprets and executes.
protocol — A set of rules or conventions.
pseudocode — A mixture of normal language and coding that provides a symbolic guide to a program.
queue — An ordered group of items waiting to be acted upon in turn.
radix — The base number in a number system that is raised to powers.
RAM — Random-access (central) memory that is reached directly.
random access — Reading or writing memory independent of storage order.
record — A collection of data items treated as a unit.
recurrence/recursion — Repetition producing new values from previous ones.
registers — Very high-speed memory used by the central processing unit.
reserved words — Words that cannot be used in an application program.
RHS — Right-hand side.
RISC — A CPU design for a reduced instruction set computer.
row-major order — The method used by Java to store matrices in which the rightmost subscript varies most rapidly and attains its maximum value before the left subscript is incremented.
run — To execute a program.
scalar — A data value or number, for example, π.
serial/scalar processing — Calculations in which numbers are processed in sequence. Contrast with vector processing and parallel processing.
shell — A command-line interpreter; the part of the operating system where the user enters commands.
SIMD — A single instruction, multiple-data computer.
simulation — The modeling of a real system by a computer program.
single precision — The use of one computer word to store a variable.
SISD — A single-instruction, single-data computer.
software — Programs or instructions.
source code — A program in a high-level language needing compilation to run.
SRAM — See static RAM.
Static RAM. — Memory that retains its contents as long as power is applied. Contrast with DRAM.
stochastic — A process in which there is an element of chance.
stride — The number of array elements stepped through as an operation repeats.
string — A connected sequence of characters treated as a single object.
structure — The organization or arrangement of a program or a computer.
subprogram — Part of a program invoked by another program unit; a subroutine.
supercomputer — The class of fastest and most powerful computers available.
superscalar — A later-generation RISC computer.
syntax — The rules governing the structure of a language.
TCP/IP — Transmission control protocol/internet protocol.
telnet — Protocols for computer–computer communications.
tera, T — Prefix indicating 1012.
top-down programming — Designing a program from the most general view of the problem down to the specific subroutines.
unary — An operation that uses only one operand; monadic.
underflow — The result of trying to store too small a number.
unit — A device having a special function.
upload — Data transfer from a local to a remote computer; the opposite of download.
URL — Universal resource locator; web address.
utility programs — Programs to enhance other programs or do chores.
vector — A group of N numbers in memory arranged in 1-D order.
vector processing — Calculations in which an entire vector of numbers is processed with one operation.
virtual memory — Memory on the slow, hard disk and not in fast RAM.
visualization — Conversion of numbers to 2-D and 3-D pictures or graphs.
volume — A physical unit of a storage medium, such as a disk.
voxel — A volume element on a regular 3-D grid.
word — A unit of main storage, usually 1, 2, 4, 6, or 8 bytes.
word length — The amount of memory used to store a computer word.