32 lines
2.1 KiB
Rexx
32 lines
2.1 KiB
Rexx
/*REXX program spits out decimal digits of pi (one digit at a time) until Ctrl-Break.*/
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signal on halt /*───► HALT when Ctrl─Break is pressed.*/
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parse arg digs oFID . /*obtain optional argument from the CL.*/
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if digs=='' | digs=="," then digs= 300 /*Not specified? Then use the default.*/
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if oFID=='' | oFID=="," then oFID='PI_SPIT2.OUT' /* " " " " " " */
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numeric digits digs /*with bigger digs, spitting is slower.*/
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q=1; r=0; t=1; k=1; n=3; L=3; z=0 /*define some REXX variables. */
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dot=1 /*DOT≡a flag when a dot in pi is shown.*/
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do until z==digs; qq= q+q /* qq is a fast version of: q*2 */
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tn= t*n /* t*n is used twice (below). */
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if qq+qq+r-t < tn then do; z= z+1 /* qq+qq is faster than qq*2 */
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call charout , n
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call charout oFID, n
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if dot then do; dot=0; call charout , .
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call charout oFID, .
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end
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nr= (r - tn) * 10
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n = ((( (qq+q+r) * 10) / t) - n*10) %1
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q = q*10
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end
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else do; nr= (qq+r) * L
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tL= t*L
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n = (q * (k*7 + 2) + r*L) / tL %1
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q = q*k
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t = tL
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L = L+2
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k = k+1
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end /* %1≡fast way doing TRUNC of a number.*/
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r=nr
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end /*forever*/
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exit /*stick a fork in it, we're all done. */
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halt: say; say 'PI_SPIT2 halted via use of Ctrl-Break.'; exit
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