generate_sphere_function: Sphere test function generator.
Description
The sphere function is arguably the simplest test function. It is
defined as
Usage
generate_sphere_function(dimensions)
Arguments
dimensions
[integer(1)] Size of parameter space.
Value
A soo_function.
Details
$$f(x) = \sum_{i=1}^n x_i^2$$
References
K. D. De Jong. An analysis of the behavior of a class
of genetic adaptive systems. PhD thesis, Department of Computer
and Communication Sciences, University of Michigan, Ann Arbor,
1975.