Exercises. 1. Read the international words and guess their meaning:

1. Read the international words and guess their meaning:

Oriented, to orient, combination, algebraic, formulae, standard, segment, constant, master, position, individual, option, representative, range, to combine, compiler, to construct, commercial, application, modular, structure, interpretation, effect, document, notation, accurate

2. Pronounce the following words correctly:

correspondent [, koris'pondə nt] v – соответствовать

several ['sevr(ə)l] a – несколько

notation [no(u)'tei ƒ (ə)n] n – исчисление, запись

familiar [fə 'miljə ] a – знакомый, известный

orient ['o: riə nt] v – ориентировать(ся)

item ['aitə m] n – элемент, единица информации

executable ['eksikju: tə bl] a – исполнимый

optional ['op ƒ ə nl] a – произвольный, необязательный

array [ə 'rei] n – массив

label ['leibl] n – метка, идентификатор, знак

enable [i'neibl] v давать возможность

general-purpose ['dʒ en(ə)r(ə)l 'pə: pə s] a – универсальный, общего назначения

feature ['fi: t ƒ ə ] n – черта, особенность, признак, свойство

emphasis ['emfə sis] n – ударение, выразительность

volume ['voljum] n – объем, большое количество, том

facility [fə 'siliti] n – доступность, pl средства, оборудование

neglect [ni'glekt] v – пренебречь, упустить из виду

reference ['refr(ə)ns] n – ссылка, сноска, эталон

whole [houl] a – целый, весь

range [rein(d)ʒ ] n – область, диапазон, интервал, ряд

imaginary [i'mæ dʒ in(ə)ri] a – воображаемый, нереальный, мнимый

true [tru: ] a истинный

false [fo: ls] a ложный

appropriate [ə 'proupriit] a – подходящий, соответствующий

precede [pri(:)'si: d] v – предшествовать

modular ['modju: lə ] a – модульный

extensive [iks'tensiv] a – расширенный, протяженный

subset [, sлb'set] n – подмножество

default [di'folt] n – упущение, недосмотр

unspecified [(')лn'spesifaid] a – не установленный, точно не определенный;

valid ['væ lid] a – действенный, обоснованный

framework ['freimwə: k] n – строение, структура, конструкция, рамки

sensitive ['sensitiv] a – чувствительный

peculiarity [pi, kju: li'æ riti] n – специфичность, особенность

3. Memorize the following word combinations:

master segment – главный сегмент

alphanumeric names – буквенно-цифровые имена

data items – элементы данных

floating-point representation – представление с плавающей точкой (запятой)

imaginary parts – мнимая часть (в комплексном числе)

truth values – истинные значения

executable statements – исполнительные операторы

assign(ment) statements – операторы присвоения

dummy variables – фиктивные переменные

to meet the needs (requirements) – отвечать требованиям

default feature – признак «по умолчанию»

valid interpretation – обоснованная интерпретация

TEXT A

HIGH LEVEL PROGRAMMING LANGUAGES: FORTRAN & PL/I

1. A high level language is a language in which each instruction or statement correspond to several machine code instructions. It is contrasted with a low level language in which each instruction has a single corresponding machine code equivalent. High level languages allow users to write in a notation with which they are familiar, e.g., FORTRAN in mathematical notation, COBOL in English. So, high level languages are oriented to the problem, while low level languages are oriented to the machine code of a computer.

2. FORTRAN. FORTRAN is an acronym for FORmula TRANslation. It is a problem oriented high level programming language for scientific and mathematical use, in which the source program is written using a combination of algebraic formulae and English statements of a standard but readable form. FORTRAN was the first high level programming language. It was developed in 1954, and was designed to easily express mathematical formulas for computer processing. It is still the most widely used programming language. There were several versions of FORTRAN. Nowadays the most popular and used is FORTRAN-4.

3. A FORTRAN program consists of data items, executable statements and non-executable statements. The program is structured in segments which consist of a master segment and optional function segments and subroutines.

4. Data items in FORTRAN are either variables or constants, and are assigned alphanumeric names by the programmer. Groups of similar items of data can be processed as arrays, or tables of data, in which case the individual items are defined by their position or reference within the array by naming the array followed by one or more subscripts.

5. Data items in FORTRAN may take the following forms: Integer isa whole number value falling within a range determined by the capacity of the computer being used. Real is a number expressed in floating-point representation accurate to a number of significant digits, the range again depends on the capabilities of the particular machine being used. Complex isa number in which two real numbers are used to express the real and imaginary parts. Logical is a quantity which can only take two values, true or false. Text is character information, which is not used for mathematical operations.

6. The actual operations of the program are expressed by means of 'executable statements'. These can take two forms: 'assignment statement' and 'control statement'. An assign statement takes the form Variable = Expression. The expression may be either arithmetic or logical. An arithmetic expression can include variables, elements, form arrays, constants and a variety of standard functions which are combined by arithmetic operations, e.g., +, —, *(multiplication), / (division), ** (exponentiation). A logical expression is similar but include the operations AND, NOT, OR, etc., and the logical operators.

7. An example of an arithmetic assignment statement would be: ROOT= (—B+SQRT (B**2—4*A*C))/ (2*A),

where the word ROOT and the letters А, В, С represent variables and SORT—the function provided for calculating square roots. The compiler recognizes these symbols and translates them into appropriate machine code. An example of a logical assignment statement would be: BOOL-A.OR.B. I In this expression the variable BOOL would be given the value true or false according to the truth values of variables A and B, and the truth table defined by the Boolean operator OR.

8. Each statement can be preceded by a numerical label, permitting reference to the statement by means of control statements. Control statements enable the program to branch to other statements. Branches themselves may also be constructed which are conditional on results of arithmetic or logical operations.

9. As was said above, a FORTRAN program consists of one or more segments, of which there is one and only one master segment, and optionally, function and subroutine segments. A function segment is used where the same form of function is required several times in a program. The statements describing the operation required to calculate the result of using the function are named and written once, and whenever the function is required in the program it is only necessary to give the function name and a list of parameters to replace the 'dummy' variables used in the function segment.

10. PL/I. PL/I was introduced in 1964. It was developed as a general-purpose programming language, incorporating features from both COBOL and FORTRAN. PL/I is used primarily on large mainframes. PL/I stands for Programming Language 1. Commercial applications (COBOL) with their emphasis on efficient handling of large volumes of data have led to the development of languages with sophisticated I/O facilities; scientific problems (FORTRAN) with their emphasis on rapid definitions and descriptions of complex problems have led to the development of highly sophisticated algorithmic languages while neglecting the data handling aspects.

11. PL/I aims at combining the problem-solving facility of scientific languages with the data-handling capabilities of commercial languages, in order to meet the needs of increasingly mathematical commercial analysis and increasingly large volumes of data being processed by scientific routines.

12. Among the more important features of PL/I are the following: (1) the language is modular in structure. This means that the user needs only master the set of facilities necessary for his programming needs. More complex problems can use more extensive subsets of the language. (2)

The language has a 'default' feature by which every error or unspecified option is given a valid interpretation, thus minimizing the effects of programming errors. (3) The language structure is 'free form'. No special documents are needed for coding, since the significance of each statement depends on its own format and not on its position within a fixed framework.

13. PL/1 is much less sensitive to the peculiarities of the hardware than the machine language. This makes it possible to use the same program on different types of computers.

14. PL/1 uses 60 symbols: 29 letters from A to Z (capital Roman letters), 10 digits from 0 to 9, and 21 special characters. The PL/I statements are subdivided into the following logical groups: input/output statements, declare statements, debugging statements, assignment statements, memory allocation statements, program structure statements, and control statements.

(To be continued)

Notes:

whenever the function is required In the program – всякий раз когда в программе требуется функция

while neglecting the data handling aspects – пренебрегая аспектами управления информацией

No special documents are needed for coding – никакие специальные документы для кодирования не требуются

capital Roman letters – заглавные латинские буквы

declare statements – операторы описания

debugging statements – операторы отладки

memory allocation statements – операторы распределения памяти