Hello Tad, It can be defined in terms of rwhnf, Matrix is strict: ghci> rwhnf $ [1,2,3,undefined::Double] () ghci> rwhnf $ (2><2) [1,2,3,undefined::Double] *** Exception: Prelude.undefined instance NFData (Matrix t) where rnf = rwhnf ms = [ident 3, (2><2) [1,2,3,undefined::Double]] ghci> rwhnf ms () ghci> rnf ms *** Exception: Prelude.undefined HTH, Alberto On 03/26/2011 06:56 PM, Tad Doxsee wrote:

Hello,

Is there already an instance of NFData (from Control.DeepSeq in the deepseq package) for the type Matrix (from Numeric.LinearAlgebra in the hmatrix package) somewhere? If not, how does one define one? (The data declaration for Matrix is in a hidden module, Data.Packed.Internal.Matrix, if that makes any difference).

Thanks,

Tad

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