30 lines
2.5 KiB
Rexx
30 lines
2.5 KiB
Rexx
/*REXX program sorts an array (using E─sort), in this case, the array contains integers.*/
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numeric digits 30 /*enables handling larger Euler numbers*/
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@. = 0; @.1 = 1
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@.3 = -1; @.5 = 5
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@.7 = -61; @.9 = 1385
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@.11= -50521; @.13= 2702765
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@.15= -199360981; @.17= 19391512145
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@.19= -2404879675441; @.21= 370371188237525
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#= 21 /*indicate there're 21 Euler numbers.*/
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call tell 'unsorted' /*display the array before the eSort. */
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call eSort # /*sort the array of some Euler numbers.*/
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call tell ' sorted' /*display the array after the eSort. */
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exit /*stick a fork in it, we're all done. */
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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eSort: procedure expose @.; parse arg N; h=N /*an eXchange sort.*/
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do while h>1; h= h%2 /*define a segment.*/
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do i=1 for N-h; j=i; k= h+i /*sort top segment.*/
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do while @.k<@.j /*see if need swap.*/
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parse value @.j @.k with @.k @.j /*swap two elements*/
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if h>=j then leave; j= j-h; k= k-h /*this part sorted?*/
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end /*while @.k<@.j*/
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end /*i*/
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end /*while h>1*/
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return
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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tell: say copies('─', 65); _= left('',9); w= length(#)
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do j=1 for #; say _ arg(1) 'array element' right(j, w)"="right(@.j, 20)
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end /*j*/
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return
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