(49G) Prime Counting Programme

[Gerald H]

For integer input the programme returns the number of prime numbers up to & including the input.

eg For input

5

the programme returns

3.

Maximum input is 1680, higher values produce an error.

Code:


::
  CK1&Dispatch
  BINT1
  ::
    ::
      %ABS
      COERCEDUP
      BINT2
      #<case
      DROPZERO
      DUP
      BINT4
      #<case
      #1-
      DUP
      # 690
      #>
      caseSIZEERR
      '
      ::
        BINT1
        #=casedrop
        ::
          #1+
          #2/
        ;
        2DUP
        #1-
        2GETEVAL
        ROT
        1GETLAM
        4PICK
        NTHCOMPDROP
        #/
        SWAPDROP
        ROT
        #1-
        2GETEVAL
        #-
      ;
      {
        BINT2
        BINT3
        BINT5
        BINT7
        BINT11
        BINT13
        2REAL
        BINT19
        BINT23
        BINT29
        BINT31
        BINT37
        BINT41
      }
      FPTR2 ^2LAMBIND
      DUP
      UNCOERCE
      %SQRT
      %IP
      COERCE
      1GETLAM
      SWAP'
      #>
      POSCOMP
      #1-DUP
      #1-UNROT
      2GETEVAL
      ABND
      #+
    ;
    UNCOERCE
  ;
;