DCL DD N    PKD(31,30);
DCL DD SQRT PKD(31,30);

DCL DD P  PKD(31, 0);
DCL DD Y  PKD(31,30);
DCL DD A  PKD(31,30);
DCL DD B  PKD(31,30);
DCL DD C  PKD(31,30);

    CPYNV        P, 4;
    CPYNV        N, 2;
    CALLI        GET-SQUARE-ROOT, *, .GET-SQUARE-ROOT;

    SUBN         Y, SQRT, 1;
    MULT         B, SQRT, 4;
    SUBN         A, 6, B;

    CPYNV        M, 3;
:   CALLI        ITERATE-PI, *, .ITERATE-PI;
    SUBN(SB)     M, 1/HI(=-1);

    RTX          *;

DCL DD WRK PKD(31,30);
DCL DD K BIN(2);
DCL INSPTR .GET-SQUARE-ROOT;
ENTRY       GET-SQUARE-ROOT INT;
    CPYNV        SQRT, 1;
    CPYNV        K, 6;
NEWTON-SQRT-ITERATION:
    DIV          WRK, N, SQRT; /* NO ROUNDING */
    ADDN(S)      SQRT, WRK;
    DIV(SR)      SQRT, 2;  /* ROUNDING MATTERS */
    SUBN(SB)     K, 1/HI(NEWTON-SQRT-ITERATION);
    B           .GET-SQUARE-ROOT;

DCL DD M  BIN(2);
DCL DD PI ZND(31,30);
DCL INSPTR .ITERATE-PI;
ENTRY       ITERATE-PI INT;
    MULT         B, Y, Y;
    MULT(S)      B, B;
    SUBN         N, 1, B;
    CALLI        GET-SQUARE-ROOT, *, .GET-SQUARE-ROOT;
    CPYNV        N, SQRT;
    CALLI        GET-SQUARE-ROOT, *, .GET-SQUARE-ROOT;
    CPYNV        B, SQRT;

    SUBN         Y, 1, B;
    ADDN         C, 1, B;
    DIV(SR)      Y, C;    /* ROUNDING IS IMPORTANT */

    ADDN         B, 1, Y;
    MULT         C, Y, Y;
    ADDN(S)      C, B;
    MULT(S)      C, Y;
    MULT(S)      C, P;

    MULT(S)      P, 4;
    MULT(S)      B, B;
    MULT(S)      B, B;
    MULT(S)      A, B;

    SUBN(S)      A, C;
    SUBN(S)      A, C;

    DIV(R)       PI, 1, A;
    CPYBLAP      MSG-TEXT, PI, " ";
    CALLI        SHOW-MESSAGE, *, .SHOW-MESSAGE;
    B           .ITERATE-PI;

%INCLUDE SHOWMSG