Blurb::  Number of scalar response functions
Description::
This keyword describes the number of scalar response functions. 
It is meant to be used in conjunction with \c field_responses, which describes
the number of field response functions.  The total number of response 
functions, both scalar and field, is given by \c response_functions.  
If only scalar responses functions are specified, it is not necessary 
to specify the number of scalar terms explicitly:  one can simply 
say \c response_functions = 5 and get 5 scalar responses. 
However, if there are three scalar responses and 2 field responses, then 
\c response_functions = 5 but \c scalar_responses = 3 and \c field_responses = 2. 

This type of data set is used by uncertainty
quantification methods, in which the effect of parameter uncertainty
on response functions is quantified, and can also be used in parameter
study and design of experiments methods (although these methods are
not restricted to this data set), in which the effect of parameter
variations on response functions is evaluated. 
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See_Also::	responses-response_functions-field_responses
