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#!F-adobe-helvetica-medium-r-normal--18*
#!N
#!CSeaGreen
#!N #!Rtcmpmod Modules: Using Compute #!N #!EC #!N #!N #!F-adobe-times-bold-r-normal--18* Compute
#!EF is a general purpose module for performing algebraic, trigonometric, and
logical operations on data. It can also extract components from vectors,
create vectors from scalar components, and cast between different data types.
#!N #!I0 #!N #!F-adobe-times-medium-r-normal--18* #!N #!N #!I30 #!N 1. Open and
execute visual program .../Compute.net. The image represents wind velocity over the
surface of the earth. Color values are based on the magnitude
of the wind velocity, and the small black squares and rectangles
represent missing data. #!N #!I30 #!N 2. Disconnect #!F-adobe-times-bold-r-normal--18* Include #!EF
from #!F-adobe-times-bold-r-normal--18* AutoColor #!EF and connect the output of #!F-adobe-times-bold-r-normal--18* Compute
#!EF to #!F-adobe-times-bold-r-normal--18* AutoColor #!EF instead. #!N #!I30 #!N 3. Execute
the visual program. Now the colors are based on the absolute
value of the x-component of the wind velocity. #!N #!I30 #!N
4. Double click on the #!F-adobe-times-bold-r-normal--18* Compute #!EF icon to open
the configuration dialog box. In this example the module has a
single input ( #!F-adobe-times-bold-r-normal--18* wind #!EF ), and the operation to
be performed is to determine the absolute value of its x-component.
#!N #!I30 #!N 5. Change "abs(wind.x)" in the #!F-adobe-times-bold-r-normal--18* Expression #!EF
field to "abs(wind.y)." and reexecute the visual program. The image changes
accordingly. #!N #!I0 #!N #!EF #!N Note: #!F-adobe-times-bold-r-normal--18* Compute #!EF is
not limited to a single input, and input tabs can be
added with the #!F-adobe-times-bold-r-normal--18* Add Input Tab #!EF function in the
#!F-adobe-times-bold-r-normal--18* Edit #!EF pull-down menu (see #!Ltadts,dxall58 h Adding Input Tabs to Tool Icons #!EL ). By default the
inputs to #!F-adobe-times-bold-r-normal--18* Compute #!EF are labeled a, b, c,..., but
you can rename them. #!N #!N It is also possible to
use #!F-adobe-times-bold-r-normal--18* Compute #!EF on components other than #!F-adobe-times-bold-r-normal--18* data #!EF
. For example, suppose you wanted to display a regular 2-D
grid of latitude and longitude on a spherical surface. You could
use #!F-adobe-times-bold-r-normal--18* Compute #!EF to convert the x,y positions of latitude
and longitude to x, y, and z positions of a spherical
surface. For an example, open and execute visual program .../WarpedGrid.net, which
generates two entirely different objects (in separate Image windows) from the
same data. #!N #!N See Compute in IBM Visualization Data Explorer
User's Reference. #!N #!N #!N #!F-adobe-times-medium-i-normal--18* Next Topic #!EF #!N #!N
#!Ltmappng,dxall82 h Modules: Using Map #!EL #!N #!F-adobe-times-medium-i-normal--18* #!N
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