Sparse N-Dimensional Arrays

This is a (still incomplete) implementation of Sparse N-Dimensional Arrays based off of GSL's SPMatrix.

Roadmap:

Operations

• allocate
• free
• get
• get variadic
• set
• set variadic
• IncrementAt
• Fill value

Arithmetic

• Addition
• Subtraction
• Simple Multiplication
• map 1/x
• Multiplication with nonzero fill values
• reduce one dimension by a given funcion

Memory Operations

• copy
• CCS compress

Fancy Operations

• Extraction of dimensions
• Reshape
• Flatten
• Partition
• Subarray extract
• Views

(PRs welcome!)