Arguments
block.obj
    An object of class gwaa.data from GenABEL.
  
block.cood
  A vector of length p+1, where p is the number of SNPs.  block.cood is an indicator vector
  that indicates block boundaries at all p+1 SNP bounded intervals.  Use
  find.bounds to create this vector.
Xa
    If block.obj is NA then a genotype matrix must be provided.  Xa is a
    matrix of genotype values codes as 0, 1 or 2 for homozygous major,
    heterozygous, or homozygous minor, respectively.
Y
    If block.obj is NA then a phenotype vector Y must be provided.  Y is a
    vector of diagnoses, where 0 is non-diseased and 1 is diseased.
  
maxcol
  The maximum number of columns allowed in the constraint matrix.  Default is 5,000.
r2.cut.min
  The lower bound of the r2.cut interval
r2.cut.max
  The upper bound of the r2.cut interval
r2.vec.length
  The number of r2.cut values uniformly spaced in r2.cut interval