# matrix-market-attoparsec

Attoparsec parser for the NIST Matrix Market format [1].

The library also contains functions for serializing to text file, and the read/write/read roundtrip works as expected.

## User guide

The module `Data.Matrix.MatrixMarket`

exports the user interface:

```
readMatrix :: FilePath -> IO (Matrix S.Scientific)
readArray :: FilePath -> IO (Array S.Scientific)
writeMatrix :: Show a => FilePath -> Matrix a -> IO ()
writeArray :: Show a => FilePath -> Array a -> IO ()
```

The first two functions contain the parsing logic, and make use of `scientific`

for parsing numerical data in scientific notation.

### Naming convention

We follow the MatrixMarket format definitions, by which a "Matrix" is *sparse* and stored in coordinate format (row, column, entry), whereas an "Array" is a *dense* grid of numbers, stored in column-oriented form.
Algebraic vectors, such as the right-hand sides of equation systems, are stored as n-by-1 Arrays.

## Testing

`test/LibSpec.hs`

contains a simple read/write/read sanity test for the included Matrix Marked data files (`fidapm05.mtx`

and `fidapm05_rhs1.mtx`

):

```
m0 <- readMatrix fname -- load original
writeMatrix ftemp m0 -- save as temp
m1 <- readMatrix ftemp -- load temp
m0 `shouldBe` m1 -- compare temp with original
```

## References

[1] http://math.nist.gov/MatrixMarket/