Jensen's Device: Difference between revisions

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=={{header|REXX}}==

<lang rexx>/*REXX program demonstrates Jensen's device (via call subroutine, and args by name). */

Note:   the 2nd and 3rd arguments for the   '''sum'''   function needn't be enclosed in quotes   (as they're numeric);

parse arg d . /*obtain optional argument from the CL.*/

they were enclosed just to be consistent with the other arguments.

if d=='' | d=="," then d= 100 /*Not specified? Then use the default.*/

<lang rexx>/*REXX program demonstrates Jensen's device (via call subroutine, and args by name).*/

~~parse arg d .;~~ if d=='' | d=="," then d=100 /*Not specified? Then use the default.*/

numeric digits d /*use D decimal digits (9 is default)*/

say 'using ' d " decimal digits:" /*display what's being used for digits.*/

say

say sum( 'i', "1", '100', "1/i" ) /*invoke SUM (100th harmonic number).*/

say sum( i, 1, 100, "1/i" ) /*invoke SUM (100th harmonic number).*/

exit /*stick a fork in it, we're all done. */

/*──────────────────────────────────────────────────────────────────────────────────────*/

sum: procedure; parse arg j,start,finish,exp; $=0

sum: procedure; parse arg j,start,finish,exp; $= 0

interpret 'do' j "=" start 'to' finish"; $=$+" exp '; end'

interpret 'do' j "=" start 'to' finish "; $=$+" exp '; end'

/* ──── ═ ─── ═════ ──── ~~══════──────────~~ ═══ ───────── */

/*comment ──── ═ ─── ═════ ──── ══════ ────────── ═══ ───────── */

/* lit var lit var lit var literal var literal */

/*comment lit var lit var lit var literal var literal */

return $</lang>