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Adding, Modifying, and Deleting Expressions


You can store frequently used expressions in the database. This provides a convenient way to remember expressions and it makes the values of these expressions available for printing and plotting. The expressions are stored in an expression table in your database. The expressions are stored in separate expression tables in your database. The convention is to name the expression table which holds the expressions associated with table TESCAL as XTESCAL. An expression table can be more generally constructed, however, so that it holds expressions for more than one table.

Since the expression values may be lengthy to calculate they are calculated and stored in a scratch file . The scratch file has the same name as your database but with an SCR  type. The file is created when needed and is deleted when any change is made to your database from LOCUS. If you've modified your database outside of LOCUS (or if you're not actively using your database), then delete its scratch file, e.g., $ DELETE TESCAL.SCR;*.

To add an expression use the Add Expression  option. Enter the name of the expression, followed by the expression. (If the expression contains any spaces, enclose it in double quotes.) See appendix B for a list of math functions and operators that can be used in the expressions.

<4=E;> Edit option? <TR>:      AE
<5> Name of expression? < >:   RETURN
    TAUNA           NE*SQRT(Q)*RMIN*RMAJ*2.04E-21
    IP15            IP>1.5
    IP_ROUND        INT4((IP+50)/100)*100
    OKTFTR          (TFTR)AND(IP>0)
    TFTR            TOKAMAK='TFTR'
<5> Name of expression? < >:   TESQ
<6> Expression? < >:           TE**2
Modify expressions with the Modify Expression  option. Enter the name of the expression that you want to change followed by the new expression. You can delete expressions with the Delete Expression  option by entering the name of the expression that you want to delete. With these options, RETURN at the name prompt will show all expressions.

Marilee Thompson
Fri Jul 11 17:05:56 EDT 1997