Figure 17-2. Linear Velocity as a Function of Time for 128 Paths 
of the Fairy Shrimp Eubranchipus Vernalis in Polarized Light. 
In principle, all behavioral variables which may be investigated using the 
Bugsystem can be generated by simple arithmetic transformation of series of X 
and Y coordinates. Greaves (4) has discussed the computation of certain 
behavioral variables (viz., linear velocity, net to gross displacement ratio, 
direction of travel and angular velocity) using arithematic operators 
implemented within the prototype system. Such operators transform every 
element of every data vector within a file, treating each vector as a separate 
unit of data. The present Bugsystem is also provided with a wide selection of 
simple arithematic operators. However, we have condensed the computation of 
certain frequently calculated behavioral variables into single operators which 
require path data as input. As an example, let us consider the RATE OF 
CHANGE OF DIRECTION operator whose command syntax is illustrated by 
the entry 
*RCDI BUGS.PA GUBS.RD nl. 
Every element in the resultant file “BUGS.RD” is the unsigned rate at which 
the corresponding path changed its direction of travel at a given moment. RCD 
is the absolute value of angular velocity expressed in degrees per second (The 
parameter “nl” is the frame rate, required to convert from degrees per frame.) 
The importance of this variable in ascertaining mechanisms responsible for 
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