36 lines
2.8 KiB
Rexx
36 lines
2.8 KiB
Rexx
/*REXX program demonstrates how to use a generator (also known as an iterator). */
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parse arg N .; if N=='' | N=="," then N=20 /*N not specified? Then use default.*/
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@.= /* [↓] calculate squares,cubes,pureSq.*/
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do i=1 for N; call Gsquare i
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call Gcube i
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call GpureSquare i /*these are cube─free square numbers.*/
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end /*i*/
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do k=1 for N; @.pureSquare.k=; end /*k*/ /*this is used to drop 1st N values.*/
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w=length(N+10); ps= 'pure square' /*the width of the numbers; a literal.*/
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do m=N+1 for 10; say ps right(m, w)":" right(GpureSquare(m), 3*w)
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end /*m*/
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exit /*stick a fork in it, we're all done. */
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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Gpower: procedure expose @.; parse arg x,p; q=@.pow.x.p
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if q\=='' then return q; _=x**p; @.pow.x.p=_
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return _
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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Gsquare: procedure expose @.; parse arg x; q=@.square.x
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if q=='' then @.square.x=Gpower(x, 2)
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return @.square.x
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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Gcube: procedure expose @.; parse arg x; q=@.cube.x
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if q=='' then @.cube.x=Gpower(x, 3) _=@.cube.x; @.3pow._=1
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return @.cube.x
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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GpureSquare: procedure expose @.; parse arg x; q=@.pureSquare.x
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if q\=='' then return q
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#=0
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do j=1 until #==x; ?=Gpower(j, 2) /*search for pure square. */
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if @.3pow.?==1 then iterate /*is it a power of three? */
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#=#+1; @.pureSquare.#=? /*assign next pureSquare. */
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end /*j*/
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return @.pureSquare.x
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