** File: Memory.hlp
** Index: 9

** Missing Value and Memory Management ****


Û  Missing values

    In the TechPlot's data sheet, all cells
take on numeric input.  They are in the
double precision format.  Any non-numeric
ASCII text, positive infinite, and negative
infinite are considered as missing values.


Û  How missing values are handled by
   functions and commands

  1.  In the mathematical calculation
    (transformation) of data columns, rows
    with missing values are ignored when
    the operations are carried out.  Where
    there are multiple columns that must be
    operated on simultaneously (such as in
    the interpolation, sorting and curve
    fitting commands), rows are ignored if
    any column has a missing value in that
    row.

  2.  The descriptive statistics result
    will show number of missing value in
    one column.

  3.  Curve Fitting and Missing Data:  All
    independent and dependent variable
    values associated with missing values
    are ignored.  Since a missing value
    reduces all columns by one row,
    TechPlot still requires the independent
    and dependent variable column lengths
    to be equal.

Û  How missing values are handled
   in graphs

    Missing values are always deleted from
all columns before they are plotted.  If a
group of columns is plotted together, the
entire row is ignored if any of the column
has a missing value in that row.


Û  Memory management

    TechPlot takes advantages of DOS
extended and expanded memory for both data
handling and plotting.  EMS is used for
both code and data management; XMS is only
used for data handling.  If you have a
choice of both EMS and XMS, EMS is
preferred.


Û  Making slides

    To make slides from your plots, you
must first convert them to a file format
that is compatible with your slide making
equipment.  Several of the file formats
available in TechPlot can be used to make
slides: HPGL (Hewlett-Packard Graphics
Language) and PIC (Lotus Picture). HPGL
has much higher resolution than PIC.  If
you are using a slide service bureau, find
which file formats are compatible with
their equipment.

