Blurb::
Size of steps to be taken in each dimension of a centered parameter study

Description::
The \c step_vector keyword defines the individual step size in each
dimension, treated separately.

<b> Default Behavior </b>

The user is required to define the number of step sizes for a centered
parameter study.  There are no default values.

Steps are taken in the plus and minus directions, and are defined in
either actual values (continuous and discrete range) or index offsets
(discrete set).

Topics::	
Examples::
\verbatim
method
  centered_parameter_study
    steps_per_variable = 5 4
    step_vector = 0.4 0.5
\endverbatim
Theory::
Faq::
See_Also::
