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From: Thomas Tschannen <tschannen%phil.UNIBE.ch%CERNVAX.BITNET@VM1.NoDak.EDU>
Subject:      SYSEVAL
To: Multiple recipients of list HP-48 <HP-48@NDSUVM1>

Hi,

Q.: Given an expression. How can you work out what variables
    there are in the expression ?

A.: Use SYSEVAL addr 353ABh

    Example 1:

        level 2:    'SIN(X)+5*Y'
        level 1:    # 353ABh

        SYSEVAL

        results in

        level 1:    { X Y }

    Example 1:

        level 2:    'SIN(COS(sin)+X)'
        level 1:    # 353ABh

        SYSEVAL

        results in

        level 1:    { sin X }

    Part of a programm to find the variables in an expression:

        DO
            DUP
            EVAL
            SWAP
            OVER
        UNTIL
            SAME
        END
        # 353ABh
        SYSEVAL


Hope somebody else can find this useful.

Thomas.

==================
----------------------------------------------------------------------------
 Thomas Tschannen                | SPAN:     20579::49203::TSCHANNEN
 Physics Institute               | BITnet:   tschannen%PHIL.unibe.ch@cernvax
 University of Berne             | INTERnet: tschannen@PHIL.unibe.ch
 Switzerland                     |