Initial data commit

Task/Proper-divisors/GFA-Basic/proper-divisors.basic

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+OPENW 1
+CLEARW 1
+'
+' Array f% is used to hold the divisors
+DIM f%(SQR(20000)) ! cannot redim arrays, so set size to largest needed
+'
+' 1. Show proper divisors of 1 to 10, inclusive
+'
+FOR i%=1 TO 10
+  num%=@proper_divisors(i%)
+  PRINT "Divisors for ";i%;":";
+  FOR j%=1 TO num%
+    PRINT " ";f%(j%);
+  NEXT j%
+  PRINT
+NEXT i%
+'
+' 2. Find (smallest) number <= 20000 with largest number of proper divisors
+'
+result%=1 ! largest so far
+number%=0 ! its number of divisors
+FOR i%=1 TO 20000
+  num%=@proper_divisors(i%)
+  IF num%>number%
+    result%=i%
+    number%=num%
+  ENDIF
+NEXT i%
+PRINT "Largest number of divisors is ";number%;" for ";result%
+'
+~INP(2)
+CLOSEW 1
+'
+' find the proper divisors of n%, placing results in f%
+' and return the number found
+'
+FUNCTION proper_divisors(n%)
+  LOCAL i%,root%,count%
+  '
+  ARRAYFILL f%(),0
+  count%=1 ! index of next slot in f% to fill
+  '
+  IF n%>1
+    f%(count%)=1
+    count%=count%+1
+    root%=SQR(n%)
+    FOR i%=2 TO root%
+      IF n% MOD i%=0
+        f%(count%)=i%
+        count%=count%+1
+        IF i%*i%<>n% ! root% is an integer, so check if i% is actual squa- lists:seq(1,10)].
+X: 1, N: []
+X: 2, N: [1]
+X: 3, N: [1]
+X: 4, N: [1,2]
+X: 5, N: [1]
+X: 6, N: [1,2,3]
+X: 7, N: [1]
+X: 8, N: [1,2,4]
+X: 9, N: [1,3]
+X: 10, N: [1,2,5]
+[ok,ok,ok,ok,ok,ok,ok,ok,ok,ok]
+
+2> properdivs:longest(20000).
+With 79, Number 15120 has the most divisors
+re root of n%
+          f%(count%)=n%/i%
+          count%=count%+1
+        ENDIF
+      ENDIF
+    NEXT i%
+  ENDIF
+  '
+  RETURN count%-1
+ENDFUNC