**Function:**`MATRIX Inverse (MATRIX`

`A`)- Returns an approximation of the inverse of the matrix
`a`.

**Function:**`MATRIX Transpose (MATRIX`

`A`)- Returns the matrix
`a`transposed.

**Function:**`MATRIX Id (INT`

`n`)- Returns an identity matrix of dimension
`n`.

**Function:**`INTERVAL_VECTOR Lower (INTERVAL_VECTOR`

`x`, INT`i`)- Splits the interval vector
`x`normal to the direction`i`and returns the lower half.

**Function:**`INTERVAL_VECTOR Upper (INTERVAL_VECTOR`

`x`, INT`i`)- Splits the interval vector
`x`normal to the direction`i`and returns the upper half.