Tímarit Verkfræðingafélags Íslands


Tímarit Verkfræðingafélags Íslands - 01.12.1974, Page 14

Tímarit Verkfræðingafélags Íslands - 01.12.1974, Page 14
.Language, er út kom árið 1962. APL er all frábrugðið öðrum for- ritunarmálum, en er mjög auðlært. Byrjandi getur, þótt hann hafi aðeins lært mjög takmarkaðan hluta máls- ins, byrjað að nota það til lausnar á verkefnum. Síðan getur hann aukið þekkingu sína smátt og smátt eftir því sem þörf krefur. Á mynd 1 er sýnt lyklaborð APL fjarritans og er það eins og á venju- legri rafmagnsritvél nema hvað tákn- in á lyklunum eru önnur. Flest tákn- in á neðri hluta lyklanna eru tölu- stafir og stórir bókstaðir en á efri hluta lyklanna eru flest táknin, ný og áður óþekkt. öll táknin svara til reikniaðgerða, sem byggðar eru inn í tölvukerfið, einnig eru til aðgerðir, sem fengnar eru fram með því að slá saman tveim táknum. Á mynd 2 er gefið yfirlit yfir allar reikniaðgerðir og tilsvar- andi tákn. Ekki verða hér útskýrðar frekar hinar ýmsu aðgerðir umfram það sem gert er á myndinni, en vís- að til einhverra þeirra bóka, sem gefnar eru upp í lok greinarinnar. Aðgerðir á vektorum og fylkjum eru mjög einfaldar og afkastamikl- Scalar Dyadic Functions Scalar Monadic Functions Mixed Functions x+y X-Y X*Y XiY X*Y X\ Y XIY X\Y X*>Y x! y XOY X<Y XZY x=y XZY X>Y X*Y *a y yvy X«Y Arvy X plus Y X minus Y X times Y X divided by Y X to the Y-th power maximum of X and Y minimum of X and Y X-residue of Y (see Table 4) base-X logarithm of Y binomial coefficient; for integer X and Y, the number of combinations of Y things taken X at a time circular and hyperbolic functions and their inverses (Y is in radians) (see Table 1) X less than Y X less than or equal to Y X equal to Y X greater than or equal to Y X greater than Y X not equal to Y X and Y Xor Y not both X and Y (X nand Y) neither X nor Y (See Table 3) + y Y -y o-y *y signof Y (-1, 0, 1) i Y reciprocal of Y * y e to the Y-th power T y ceiling of Y L y floor of Y | y magnitude of Y ®y natural logarithm of Y ! y factorial Y; Gamma function of Y + 1 oy v times Y ?Y a random integer from the vector i Y ~y not Y result 0 if it is 1 if the relation holds, does not Ooy (1-Y*2)*.5 loy sin Y 2oy cos Y 3oy tan Y uoy (1+Y*2)*.5 5oy sinh Y 6oy cosh Y 7oy tanh Y inverse functions are given by negative values of X, i.e. loy = arcsin Y. Table 1 X y A a y xvy X*Y Avy 0 0 0 0 1 1 0 í 0 1 1 0 1 0 0 í 1 0 1 í 1 1 0 0 Table 2 y ry U 3.14 4 3 3.14 ” 3 4 Table 3 X\X x*o X X X X X x-o y xpy py XÍYH X\Y i y XeY XtY XiY X?Y A4>y A4>czjy XQY 4>y 4>[zjy ey X$Y $y XtY ,y X\Y XiY X+Y 4A Reshape Y to have dimension X Dimension of Y The elements of X at locations Y First location of Y within vector X The first Y consecutive integers from Origin (0 or 1 as set by set origin command) Each element of X c Y is 1 or 0 if the corresponding element of X is or is not some element of Y Representation of Y in number system X Value of the representation Y in number system X X integers selected randomly without repetition from iY Rotation by X along the last dimension of Y Rotation by X along the Zth dimension of Y Rotation by X along the first dimension of Y Reversal along the last dimension of Y Reversal along the Zth dimension of Y Reversal along the first dimension of Y Transpose by X of the coordinates of Y Ordinary transpose of Y Y catenated to X Ravel of Y (make Y a vector) I If X positive take first X elements of Y Mf X negative take last |X elements of Y I If X positive leave first X elements of Y I If X negative leave last IX elementsofY X specified by Y The indices of values of the vector X in sorted ascending order The indices of values of the vector X in sorted descending order Null See Program Definition Section Comment In the entries below o stands for ''any scalar dyadic operator" Generalized Reduction i.e., insert the symbol o between each pair of elements of Y Table 4 Special Symbols ) Parentheses. Expressions may be of any complexity and are executed from right to left except as indicated by parentheses. < Branch to X, where X is a scalar or vector. If X is an empty vector, go to the next line in sequence. If X is not in the range of statement numbers in the function, leave the function. o/y The o reduction along the last dimension of Y o/[Zjy The o reduction along the Zth dimension of Y o/y The © reduction along the first dimension of Y Compression and Expansion X/Y X (logical) compressing along the last dimension of Y X/[ ZJY X (logical) compressing along the Zth dimension of Y X/Y X (logical) compressing along the first dimension of Y X\Y X (logical) expanding along the last dimension of Y X\[ Z jy X (logical) expanding along the Zth dimension of Y X\Y X (logical) expanding along the first dimension of Y -v Terminate execution of a suspended function. Print the value of X. The value of any expression or variable is also printed if no assignment is made. A*-D Request input. Value of □ is the resulting value after expression entered is evaluated. Request input. Value of □ is entire input text as literal characters, up to but not including carrier return. 'XYZ’ The literal characters XYZ. Underline: Allows increased set of alphabetic characters, i.e., A and A are both distinct characters. Generalized Matrix Operations X+ . *Y Ordinary matrix product of X and Y Xo . o'y Generalized inner product of X and Y X° . ©y Generalized outer product of X and Y All scalar functions are extended to operate element-by-element on dimensioned operands; i.e., vectors, matrixes, and higher-dimensional arrays. A scalar or one-component vector may be used as one argument of a scalar dyadic function and will be extended to conform to the dimen- sion of the other argument. Overstruck Symbols ®wv4>í9i » ?4vCjA/\e Mynd 2. APL táknin. 92 — TlMARIT VFÍ 1974

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