NormalEquation (file format)

Stores a system of normal equations \[ \M N \hat{\M x} = \M n. \] This file format consists of multiple files. The file name normals.dat.gz corresponds to the following files:

• normals.dat.gz or normals.00.00.dat.gz ... normals.0n.0n.dat.gz: the normal matrix $\M N$ as matrix,
• normals.rightHandSide.dat.gz: the right hand side(s) $\M n$ as matrix,
• normals.parameterNames.txt: parameter names,
• normals.info.xml: u.a. containing the number of observations and the quadratic sum of (reduced) observations $\M l^T\M P\M l$.

A large normal matrix may be splitted into blocks and stored in multiple files. The block row/column number is indicated in the file name. Only the upper blocks of the sysmmetric matrix are considered. Matrix in blocks can be distributed on muliple nodes in parallel mode to efficiently use distributed memory.