mu_calc: mu Calculator
In SparseMDC: Implementation of SparseMDC Algorithm

This function handles the calculations of the Mu Solver. This function runs inside sparse_mdc.

1	mu_calc(d, v, EQ, dim, x, nk, p1, p2, delta)

`d`	- The current condition.
`v`	- Relationship matrix, describing relationship between d-1 and d.
`EQ`	- Equality matrix specifying the number of following terms to which mu_d is equal.
`dim`	Total number of conditions, D.
`x`	- Matrix of mean values.
`nk`	- Vector with the number of samples in each dimension for this cluster.
`p1`	- Penalties on mean size.
`p2`	- Penalties on mean difference.
`delta`	Small term to ensure existance of solution.