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Barrons Publishing Dictionary of Computer and Internet Terms 10th

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flush

196

The flowchart in Figure 108 shows how to calculate the cube root of a number a using Newton’s method, where x is the guess for the cube root of a, and δ indicates how accurate the result must be. The procedure will follow around the loop until |x3 – a| < δ.

“Start” and “stop” statements are written with ovals, action statements are written with squares, and decision statements are written in diamonds. A decision statement asks a yes-or-no question. If the answer is yes, the path labeled “yes” is followed; otherwise, the other path is followed.

Writing a flowchart often helps to solve a complex programming problem, although flowcharts are seldom used now that structured programming has become popular. A flowchart is often much bulkier than the program it describes. See STRUCTURED PROGRAMMING.

FIGURE 108. Flowchart

flush

1.flat against a margin, as in FLUSH RIGHT and FLUSH LEFT.

2.to finish an output operation by emptying the buffer in which the information is stored while waiting to be output.

flush left an arrangement of text with each line starting at the same horizontal position, making a neat left edge. Flush left, ragged right means

197

FOAF

that the length of the lines are allowed to vary. The right edge looks like a torn piece of paper—in other words, ragged.

This is

an example of some flush-left type.

Flush left is how type is ordinarily arranged on a typewriter.

Contrast CENTER; FLUSH RIGHT; JUSTIFICATION.

flush right an arrangement of text with each line of type ending at the same horizontal position. The beginnings of the lines are irregular, but the right margin is smooth.

This is an example of flush-right type.

Flush-right alignment is seldom used except in charts or tables.

Contrast CENTER; FLUSH LEFT; JUSTIFICATION.

fly-in see TRANSITION EFFECT.

fly-out menu a secondary menu that appears to the side when you select an item on the primary menu.

FIGURE 109. Fly-out menus

FM synthesis (frequency modulation synthesis) a technique of synthesizing musical sounds by using one waveform to modulate (vary) the frequency of another waveform. FM synthesis is an older technique for generating electronic music. It produces a wide variety of sounds, but it does not imitate conventional musical instruments as closely as

WAVETABLE SYNTHESIS does. Contrast WAVETABLE SYNTHESIS.

FOAF (slang) friend of a friend, an unidentified source of a piece of information. See HOAX.

CROP FACTOR; F-STOP; ZOOM (definition 2).

focal length

198

focal length the distance from a lens to the focal plane, or in the case of a multi-element lens, the focal length of a simple lens that would form the same size image.

A longer focal length produces a larger image and covers a narrower field. On a 35-mm camera, a “normal” lens has a focal length of about 50 mm; wide-angle lenses are 20 to 40 mm, and telephoto lenses are 80 to 200 mm or longer.

Electronic image sensors are usually much smaller than film, and they require shorter-focal-length lenses to cover the same field. The focal length of such lenses is sometimes specified as “35-mm equivalent,” (i.e., the focal length that would cover the same field of view on 35-mm film). Typically, the true focal length is written on the lens, and the 35-mm equivalent is used in advertising.

The focal length of a ZOOM lens is variable (Figure 110). A lens marked “3× zoom” has a focal length that is three times as long at maximum as at minimum.

See also

FIGURE 110. Focal length (7–14 mm) and f-ratio (f / 3.5–f / 4.8) (both variable on this zoom lens)

focus the part of a DIALOG BOX that is ready to receive input from the keyboard. The focus is generally indicated by highlighting with a special color or with an extra dotted line around a BUTTON.

folder a directory (on the Macintosh or in Windows). See DIRECTORY.

font a complete collection of characters (including upperand lowercase letters, numerals, punctuation, ligatures, reference marks, etc.) in a consistent style and size. Desktop publishing programs and word processors let you use more than one font in a single document. When you switch to italics or to bold or to a larger size, you are changing the font even though you may still be in the same TYPEFACE.

Some fonts are specifically designed to be printed at a particular size. For instance, if you have 8-point Dutch Roman and 12-point Dutch Roman on your laser printer font cartridge, you cannot use intermediate sizes such as 9-point. If the largest font you have is 72 points, then you will not be able to set 96-point type. Current systems use SCALABLE FONTs that can be used at any size. See also TRUETYPE FONT; TYPE 1 FONT.

199

for

FIGURE 111. Font (Times New Roman)

foot the bottom of the page. Contrast HEAD.

footer text that is placed at the bottom of each page of a printed document. Contrast HEAD (definition 2).

footnote a short comment placed at the bottom (FOOT) of a page that provides a citation or insightful comment to the text.* Some word processors cannot handle footnotes properly, placing them at the end of the chapter or article rather than at the foot of the page where they belong.

Footnotes should be numbered consecutively throughout an entire book, or beginning again for each chapter or page. Sometimes footnotes are not numbered, but are referenced by a traditional set of symbols. They should be used in this order: ASTERISK (*), DAGGER (†), DOUBLE DAGGER (‡), SECTION SIGN (§), and PILCROW (¶).

footprint the amount of space on a desk that a device takes up. For example, a laptop computer has a smaller footprint than a full-size PC. A smaller footprint is desirable because it leaves more space for other items on your desk. See also REAL ESTATE.

for a keyword that identifies one type of loop in several programming languages. A for loop causes a certain variable, known as the loop variable, to take on several values in sequence. For example, this Java code prints out the whole numbers from 1 to 10:

/* This is Java: */

for (int i=1; i<=10; i++)

{

System.out.println(i);

}

A for loop can be used either to obtain repetition or to make the values of the variable available for some purpose. For example, here is how to calculate the sum of the whole numbers from 1 to 100 in Java:

*This is a footnote. Notice that the asterisk in the footnote matches the asterisk in the text. The typeface used for the footnote is smaller than the font used for the body copy. A horizontal rule or extra vertical space should be used to separate the footnote from the text.

force quit

200

int t=0;

for (int i=1; i<=100; i++)

{

t=t+i;

}

System.out.println(t);

Although the statements within the loop can examine the value of the loop variable, they should not attempt to change it, since the result of doing so is unpredictable.

In C, C++, Java, and C#, the for statement is more general; it takes the form

for (init; test; step) {statements}

where init is a statement that is executed once, before beginning the loop; test is a condition that must be true at the beginning of every pass through the loop; step is a statement executed at the end of each pass; and statements are the statements within the loop, if any. Unlike its BASIC and Pascal counterparts, this kind of for statement need not step a number through a series of values; it can be used for many other kinds of repeated actions, because init, test, and step can be statements and tests of any kind. Compare DO; WHILE.

force quit (Macintosh) to escape from a frozen or hung program by pressing the Option, Command (z), and Escape keys simultaneously. This brings up a dialog box listing all active applications. Choose the name of the frozen program and click ”Force Quit.”

See FREEZE UP; HANG; CRASH. Compare TASK MANAGER.

form a screen display in which the user is expected to type in information and then press Enter or click OK. Forms enable readers of WEB PAGEs to send information to the host site.

form factor the size and shape of a piece of equipment or material. Diskette drive form factors include half-height and full-height. Motherboard form factors include AT (like the original PC AT), “Baby AT” (a smaller board that mounts in the same case), and ATX (a newer type of motherboard introduced by Intel and others in 1996).

form feed the character code (ASCII decimal 12, Ctrl-L) that causes a printer to eject the current sheet of paper and start a new one. Compare LF (line feed).

form, HTML a web page that allows users to enter data, which can then be sent back to the server. Here is an example of the HTML code for a form where users can enter an e-mail address into a text field, use a list box to select either the deluxe, special, or standard version; use radio buttons to indicate which region they are from; use a check box to indicate whether they are a first-time visitor or not; and enter a brief message into a text area.

201

form, HTML

The ACTION command of this form will simply e-mail the result of the form to the specified address. It is also possible to specify a CGI script as the ACTION. This script needs to be specially written to process the results of the form once they are sent back to the server. The text that is not enclosed by < > are labels; see Figure 113, which shows how this form appears on the screen. Each element of the form needs to have a name by which it is identified to the server; in this example, the names are EMAIL, VERSION, NEWVISITOR, REGION, and MESSAGETEXT. Finally, the form has a submit button for the user to click when ready to send the information, and a reset button to clear information if desired.

For another example of an HTML form, see JAVASCRIPT.

<HTML>

<HEAD>

<TITLE>Form Example</TITLE> </HEAD>

<BODY>

<H2>Example of an HTML Form</H2>

<FORM METHOD=POST ACTION=MAILTO:yourcompany@xyz.com> Enter your e-mail address:

<INPUT TYPE=TEXTNAME=EMAILWIDTH=25> <BR>

Choose which version you prefer: <SELECT NAME=VERSION>

<OPTION SELECTED> Standard <OPTION> Special

<OPTION> Deluxe </SELECT>

<BR>

Indicate which region you are from:<BR>

<INPUT NAME=REGIONTYPE=RADIOVALUE=North>North <INPUT NAME=REGIONTYPE=RADIOVALUE=South>South <INPUT NAME=REGIONTYPE=RADIOVALUE=East>East <INPUT NAME=REGIONTYPE=RADIOVALUE=West>West <BR>

Are you a new visitor?

<INPUT TYPE=CHECKBOXNAME=NEWVISVALUE=yes> <BR>

<TEXTAREA COLS=40 ROWS=5 NAME=MESSAGETEXT> Type your message here,

as many lines as you want...

</TEXTAREA>

<BR>

<INPUT TYPE=SUBMIT

VALUE=Click here to submit message> <INPUT TYPE=RESET

VALUE=Click here to clear all data> </FORM>

</BODY>

</HTML>

FIGURE 112. Form, HTML (source code)

formal parameter

202

FIGURE 113. Form, HTML (as displayed on screen)

formal parameter a name used within a function or subroutine for a value that will be passed to it from the calling program. Contrast ACTUAL PARAMETER.

format any method of arranging information that is to be stored or displayed. The word format can therefore refer to many different things relating to computers. Three of its most common uses are as follows:

1.The format of a file (or of any storage medium) refers to the way the information is stored in it. See FILE FORMAT.

2.To format a disk is to make the computer record a pattern of reference marks on it, which is usually done at the factory. Formatting a disk erases any information previously recorded on it.

3.In spreadsheets and programming languages, the format of a data item determines its appearance (how many digits are displayed, whether there is a dollar sign, etc, whether to use italics, etc).

formatting the special codes in a document that indicate italics, underlining, boldface, and the like. Formatting information is lost when a file is saved as ASCII text.

FORTH a programming language invented by Charles Moore around 1970. FORTH is noted for requiring few machine resources and giving very rapid execution.

In FORTH, programmers define their own statements in terms of simpler statements. FORTH is a threaded interpretive language, meaning that a program is represented in the computer as a list of addresses of subroutines, each of which is composed of addresses of other subroutines, and so on until the primitive operations of the language are reached. Because it has little to do except read addresses and jump to

203

FORTRAN

them, a FORTH interpreter can run very fast; in fact, there is little difference between an interpreter and a compiler for FORTH.

C FORTRAN IV program to

C find sum of integers 1-100 INTEGER I, SUM

SUM=0

DO 1 I=1, 100

1 SUM =SUM + I

WRITE (6,2) SUM

2 FORMAT(1X,I5) STOP

END

FIGURE 114. FORTRAN IV program

FORTRAN (Formula Translation) a programming language developed by IBM in the late 1950s, the first major programming language that allowed programmers to describe calculations by means of mathematical formulas. Instead of writing assembly language instructions such as

LOAD A

ADD B

MULTIPLY C

STORE D

the FORTRAN programmer writes

D = (A+B)*C

where * is the symbol for multiplication. Almost all subsequent programming languages have adopted this useful feature.

FORTRAN has existed in several versions, of which the most important are FORTRAN IV (USASI Standard FORTRAN, 1966) and FORTRAN 77 (ANSI FORTRAN, 1977). Figure 114 shows a sample FORTRAN IV program.

Comments begin with C in column 1; all other statements begin in column 7, though they may have numbers in columns 2–5. Any line with column 6 nonblank is treated as a continuation of the previous statement.

The FORMAT statement in the example specifies that the output should consist of a single blank, followed by an integer occupying 5 character positions. The blank is not actually printed; it serves as carriage control and tells the printer to print a new line in the normal manner. This is a relic of early IBM printers that used the first character of each line as a control code for various printer functions. The number 6 in the WRITE statement refers to the printer—another relic of early IBM computer architecture.

FORTRAN variable names contain up to six letters or digits; the first character must be a letter. Variables can be declared as INTEGER, REAL (floating-point), DOUBLE PRECISION (like real, but with more significant digits), COMPLEX (see COMPLEX NUMBER), LOGICAL (Boolean), or (in FORTRAN 77) CHARACTER. If a variable is not declared, it is assumed to be integer if its name begins with I, J, K, L, M, or N, or real otherwise.

forward

204

Compared to FORTRAN IV, FORTRAN 77, and FORTRAN 90 include more sophisticated input-output statements, especially for file handling, the ability to process character-string data, and block-struc- tured IF-ELSE-ENDIF statements to facilitate structured programming.

See STRUCTURED PROGRAMMING.

forward to send a piece of e-mail on to another person, with an indication that you received it and forwarded it. Contrast BOUNCE (definition 2).

forward button on a web browser, the button that returns you to where you were before you clicked on the “back” button.

forward one a graphics program command that moves the selected object up one in the stacking order. See also BACK ONE; DRAW PROGRAM; SEND TO BACK; SEND TO FRONT; VECTOR GRAPHICS.

forward one; bring forward comparable commands that send the selected object down one layer. See also ARRANGE; BACK ONE; BRING FORWARD;

BRING TO FRONT; DRAW PROGRAM; SEND BACKWARD; SEND TO BACK; TO BACK; TO FRONT.

fountain fill a fill that is composed of two or more colors. In between the colors is a smooth blending. You are able to rotate the angle of the fill (linear) or have the blend radiate from a central point (radial). Figure 115 shows a sampling of different fountain fills. See also UNIFORM FILL. Also called a GRADIENT FILL.

FIGURE 115. Fountain fills

fourth-generation computers computers built around integrated circuits with large-scale integration. Some people view these computers as being advanced third-generation computers.

Foveon a type of high-resolution CMOS image sensor developed by Foveon, Inc. (www.foveon.com) and National Semiconductor Corporation. Unlike earlier color image sensors, the Foveon has separate layers sensitive to red, green, and blue light, so the image color is sensed accurately in every pixel, and no light is discarded in colored filters. See

CCD IMAGE SENSOR; CMOS IMAGE SENSOR. Contrast BAYER MATRIX.

The name Foveon presumably alludes to fovea, the Latin name for the central, color-sensitive part of the retina of the human eye.

FPS

1.(Frames Per Second) the rate at which a moving image is generated or transmitted. All moving images are actually sequences of still pictures. See ANIMATION.

2.abbreviation for FIRST PERSON SHOOTER.

205

fragmentation

fractal a shape that contains an infinite amount of fine detail. That is, no matter how much a fractal is enlarged, there is still more detail to be revealed by enlarging it further. Fractals are common in nature; they are the shapes of clouds, coastlines, broken rocks, the edges of torn pieces of paper, and the like. Fractals are important in generating realistic images of everyday objects on the computer.

Figure 116 shows how to construct a fractal called a Koch snowflake. Start with a triangle and repeatedly replace every straight line with a bent line of the form:

The picture shows the result of doing this 0, 1, 2, and 3 times. If this were done an infinite number of times, the result would be a fractal.

FIGURE 116. Fractal built from a triangle (the Koch snowflake)

fragmentation a situation in which many files on a hard disk are broken into little chunks and stored in physically different areas of the disk platter. This can dramatically slow down access time and create long waits while files are being read or written.

A disk becomes fragmented when many files are created and erased on it over a long period of time. Files are recorded continuously on an empty disk, but as files of various sizes get erased, empty spots develop that gradually become filled in with parts of newly recorded files. Eventually, when the user creates a large file, the file will be given space in many disconnected places all over the disk (see Figure 117 for an illustration).

To defragment a disk in Microsoft Windows, open “Computer,” rightclick on the disk, and choose Properties and then Tools.

FIGURE 117. Fragmentation

(dark areas show sectors occupied by one file)

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