33 lines
2.8 KiB
Rexx
33 lines
2.8 KiB
Rexx
/*REXX program generates some random numbers, shows bin histogram, finds mean & stdDev. */
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numeric digits 20 /*use twenty decimal digits precision, */
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showDigs=digits()%2 /* ··· but only show ten decimal digits*/
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parse arg size seed . /*allow specification: size, and seed.*/
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if size=='' | size=="," then size=100 /*Not specified? Then use the default.*/
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if datatype(seed,'W') then call random ,,seed /*allow a seed for the RANDOM BIF. */
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#.=0 /*count of the numbers in each bin. */
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do j=1 for size /*generate some random numbers. */
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@.j=random(, 99999) / 100000 /*express random number as a fraction. */
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_=substr(@.j'00', 3, 1) /*determine which bin the number is in,*/
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#._=#._ + 1 /* ··· and bump its count. */
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end /*j*/
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do k=0 for 10; kp=k + 1 /*show a histogram of the bins. */
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lr='0.'k ; if k==0 then lr= "0 " /*adjust for the low range. */
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hr='0.'kp ; if k==9 then hr= "1 " /* " " " high range. */
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barPC=right( strip( left( format( 100*#.k / size, , 2), 5)), 5) /*compute the %. */
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say lr"──►"hr' ' barPC copies("─", barPC * 2 % 1 ) /*show histogram.*/
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end /*k*/
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say
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say 'sample size = ' size; say
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avg= mean(size) ; say ' mean = ' format(avg, , showDigs)
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std=stdDev(size) ; say ' stdDev = ' format(std, , showDigs)
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exit /*stick a fork in it, we're all done. */
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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mean: arg N; $=0; do m=1 for N; $=$ + @.m; end; return $/N
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stdDev: arg N; $=0; do s=1 for N; $=$ + (@.s-avg)**2; end; return sqrt($/N) /1
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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sqrt: procedure; parse arg x; if x=0 then return 0; d=digits(); m.=9; numeric form; h=d+6
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numeric digits; parse value format(x,2,1,,0) 'E0' with g 'E' _ .; g=g*.5'e'_ % 2
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do j=0 while h>9; m.j=h; h=h%2+1; end /*j*/
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do k=j+5 to 0 by -1; numeric digits m.k; g=(g+x/g)*.5; end /*k*/; return g
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