FPRIMES 2 24 68 RPRIMES N;P;V;ÉIO ÉIO P V 1,2Nµ1 0 L:PP+(PV)∞1 V[P⌡1∞ N÷P] L ⌐∞N≥P*2 RV/∞ N Σ LINE 0 DEFINES THE FUNCTION: NAMES IT, CALLS FOR AN EXPLICIT Σ RESULT 'R ', REQUIRES A RIGHT ARGUMENT 'N', AND LOCALIZES Σ TEMPORARY VA RIABLES. Σ LINES 1-3 INITI ALIZE THE VARIABLES: THE INDEX ORIGIN IS SET Σ TO 1 (IN MOST FUNC TIONS 0 IS PREFERABLE FOR ABOUT A DOZEN Σ REASONS); 'P' AND 'V' ARE DEFINED, THE LATTER IN TERMS OF 'N'. Σ LINES 4-7 ARE THE EQUIVA LENT OF A RECURSIVE FUNCTION: Σ - THE NEXT VALUE OF 'P' I S FOUND Σ - MULTIPLES OF THE P'TH POSI TION IN 'V' ARE ZEROED OUT Σ - THE PROCESS IS REPEATED IF 'N ' IS ≥ 'P' SQUARED Σ - OTHERWISE, THE RESULT IS CALCULA TED AS THE NUMBERS FROM Σ - 1 THROUGH 'N' WHICH ARE NOT ZERO IN THE VECTOR 'V'. Σ GIVEN ENOUGH MEMORY IN ONE'S MACHINE, THIS <PRIMES> FUNCTION Σ WILL WORK FOR N≤32761 ON THE APL*PLUS/PC SYST EM OF STSC, INC., Σ SINCE IT HAS AN OBJECT SIZE LIMIT OF 65536 BYTES - THE AMOUNT Σ NEEDED TO REPRESENT THE VECTOR 'V' INCLUDING 14 BYT XES OF OVERHEAD.
