PortaCalc Mini-Tutorial
	  LOOKUP

	The LOOKUP function is commonly found in commercial spread
sheets. This is not directly present on PortaCalc, but is simple to
obtain.
	The LOOKUP function is given a cell and a table to look up
in, and it searches the table for the next larger element than the
cell given (or the entry just before this; the definition is easily
tailored in PortaCalc) and returns the next element in the matrix right
or down from the cell found.
	In the example sheet of Fig. 1, the matrix from A2 to D3 is
the lookup table. The desired action is to search for the entry in
the row A2:D2 which is greater than the chosen cell, and return the
next cell down from that entry.
	To do this, we use the formula in cell B6. Accumulator A is
used to hold the value we look for, accumulator B holds the length
of the row we look in, and we start an indirect file having moved
to cell A2, the upper left cell of the row. The command file invoked
scans right until either B counts down (using up the count) or until
we find the desired cell. Since in this case we look for a cell larger
than 15., we find cell C2. The command file then returns the next
lower value (3. in this case). Note if we were searching a column
instead of a row, a simple approach would have been to call a
different indirect file.
	The command file is exhibited below the sheet. Note its use
of the locate function *P cell to move to relative cells, and the *J
construct, which jumps ONLY if the last calculation resulted in a
number that is larger than 0.
	The following are the figures:


 Demonstration of LOOKUP functionality in PortaCalc
ROW/COL   A= 1      B= 2                               C= 3          D= 4
    1>           Cell range A2:D2 has values, A3:D3 has results              
    2> 6.        11.                                35.           76.        
    3> 1.        2.                                 3.            4.         
    4>                                                                       
    5>           Next line holds lookup for A6                               
    6> 15.       A=A6\B=4.\*P A2\*@LKPRW.CMD                                 
    7>                                                                       
	FIG. 1 - SHEET using a lookup function in cell B6

*C LOOKUP ROW. 
*C USE: A=VBL TO TEST\B=ROW LENGTH\*P LOOKUP START\*@LKPR.CMD
*C LOOP
%=(P#0#0)-A
*J GOTIT
*P P#1#0
B=(B)-1.
*J LOOP
*C GOTIT
%=P#0#1
	Fig. 2 - LKPRW.CMD command file called by sheet of Fig 1


	Had it been desired to retrieve the cell to the left of the one
gotten, the last line might have been replaced in the command file with

   %=P#-1#1

which would retrieve the cell to the left of the one currently
returned.
	Similar techniques can be used for other sorts of searches.
Note the *G construct more or less directly handles the functionality
of the CHOOSE function of most spreadsheets.