Add tasks for all the new languages

Task/Van-der-Corput-sequence/ERRE/van-der-corput-sequence.erre

@@ -0,0 +1,27 @@
+PROGRAM VAN_DER_CORPUT
+
+!
+! for rosettacode.org
+!
+
+PROCEDURE VDC(N%,B%->RES)
+      LOCAL V,S%
+      S%=1
+      WHILE N%>0 DO
+        S%*=B%
+        V+=(N% MOD B%)/S%
+        N%=N% DIV B%
+      END WHILE
+      RES=V
+END PROCEDURE
+
+BEGIN
+      FOR BASE%=2 TO 5 DO
+        PRINT("Base";STR$(BASE%);":")
+        FOR NUMBER%=0 TO 9 DO
+          VDC(NUMBER%,BASE%->RES)
+          WRITE("#.##### ";RES;)
+        END FOR
+        PRINT
+      END FOR
+END PROGRAM

Task/Van-der-Corput-sequence/FreeBASIC/van-der-corput-sequence.freebasic

@@ -0,0 +1,42 @@
+' version 03-12-2016
+' compile with: fbc -s console
+
+Function num_base(number As ULongInt, _base_ As UInteger) As String
+
+    If _base_ > 9 Then
+        Print "base not handled by function"
+        Sleep 5000
+        Return ""
+    End If
+
+    Dim As ULongInt n
+    Dim As String ans
+
+    While number <> 0
+        n = number Mod _base_
+        ans = Str(n) + ans
+        number = number \ _base_
+    Wend
+
+    If ans = "" Then ans = "0"
+
+    Return "." + ans
+
+End Function
+
+' ------=< MAIN >=------
+
+Dim As ULong k, l
+For k = 2 To 5
+    Print "Base = "; k
+    For l = 0 To 12
+        Print left(num_base(l, k) + "      ",6);
+    Next
+    Print : print
+Next
+
+' empty keyboard buffer
+While Inkey <> "" : Wend
+Print : Print "hit any key to end program"
+Sleep
+End

Task/Van-der-Corput-sequence/Phix/van-der-corput-sequence.phix

@@ -0,0 +1,44 @@
+enum BASE, FRAC, DECIMAL
+constant DESC = {"Base","Fraction","Decimal"}
+
+function vdc(integer n, atom base, integer flag)
+object res = ""
+atom num = 0, denom = 1, digit, g
+    while n do
+        denom *= base
+        digit = remainder(n,base)
+        n = floor(n/base)
+        if flag=BASE then
+            res &= digit+'0'
+        else
+            num = num*base+digit
+        end if
+    end while
+    if flag=FRAC then
+        g = gcd(num,denom)
+        return {num/g,denom/g}
+    elsif flag=DECIMAL then
+        return num/denom
+    end if
+    return {iff(length(res)=0?"0":"0."&res)}
+end function
+
+procedure show_vdc(integer flag, string fmt)
+object v
+    for i=2 to 5 do
+        printf(1,"%s %d: ",{DESC[flag],i})
+        for j=0 to 9 do
+            v = vdc(j,i,flag)
+            if flag=FRAC and v[1]=0 then
+                printf(1,"0 ")
+            else
+                printf(1,fmt,v)
+            end if
+        end for
+        puts(1,"\n")
+    end for
+end procedure
+
+show_vdc(BASE,"%s ")
+show_vdc(FRAC,"%d/%d ")
+show_vdc(DECIMAL,"%g ")

Task/Van-der-Corput-sequence/Ring/van-der-corput-sequence.ring

@@ -0,0 +1,19 @@
+decimals(4)
+for base = 2 to 5
+    see "base " + string(base) + " : "
+    for number = 0 to 9
+        see "" + corput(number, base) + " "
+    next
+    see nl
+next
+
+func corput n, b
+     vdc = 0
+     denom = 1
+     while n
+           denom *= b
+           rem = n % b
+           n = floor(n/b)
+           vdc += rem / denom
+     end
+     return vdc

Task/Van-der-Corput-sequence/Sidef/van-der-corput-sequence.sidef

@@ -0,0 +1,15 @@
+func vdc(value, base=2) {
+    while (value[-1] > 0) {
+        value.append(value[-1] / base -> int);
+    }
+    var (x, sum) = (1, 0);
+    value.each { |i|
+        sum += ((i % base) / (x *= base));
+    }
+    return sum;
+}
+
+2.to(5).each { |base|
+    var seq = (10.range.map {|i| vdc([i], base) });
+    "base %d: %s\n".printf(base, seq.map{|n| "%.4f" % n}.join(', '));
+}

Task/Van-der-Corput-sequence/jq/van-der-corput-sequence-1.jq

@@ -0,0 +1,16 @@
+# vdc(base) converts an input decimal integer to a decimal number based on the van der
+# Corput sequence using base 'base', e.g. (4 | vdc(2)) is 0.125.
+#
+def vdc(base):
+
+  # The helper function converts a stream of residuals to a decimal,
+  # e.g. if base is 2, then decimalize( (0,0,1) ) yields 0.125
+  def decimalize(stream):
+    reduce stream as $d   # state: [accumulator, power]
+      ( [0, 1/base];
+       .[1] as $power | [ .[0] + ($d * $power), $power / base] )
+    | .[0];
+
+  if . == 0 then 0
+  else decimalize(recurse( if . == 0 then empty else ./base | floor end ) % base)
+  end ;

Task/Van-der-Corput-sequence/jq/van-der-corput-sequence-2.jq

@@ -0,0 +1,5 @@
+def round(n):
+  (if . < 0 then -1 else 1 end) as $s
+  | $s*10*.*n | if (floor%10)>4 then (.+5) else . end | ./10 | floor/n | .*$s;
+
+range(2;6) | . as $base | "Base \(.): \( [ range(0;11) | vdc($base)|round(1000) ] )"

Task/Van-der-Corput-sequence/jq/van-der-corput-sequence-3.jq

@@ -0,0 +1,5 @@
+$ jq -n -f -c -r van_der_corput_sequence.jq
+Base 2: [0,0.5,0.25,0.75,0.125,0.625,0.375,0.875,0.063,0.563,0.313]
+Base 3: [0,0.333,0.667,0.111,0.444,0.778,0.222,0.556,0.889,0.037,0.37]
+Base 4: [0,0.25,0.5,0.75,0.063,0.313,0.563,0.813,0.125,0.375,0.625]
+Base 5: [0,0.2,0.4,0.6,0.8,0.04,0.24,0.44,0.64,0.84,0.08]