added MinimalGenerators as option for dual of matrices and complexes

TODO: should dual of modules call Hom(M, R^1) and
use the same optional argument as well?

M2/Macaulay2/m2/chaincomplexes.m2

@@ -643,9 +643,7 @@ Hom(Module, ChainComplex) := ChainComplex => opts -> (M, C) -> (
 	       ));
      D)
 
-dual ChainComplex := ChainComplex => {} >> o -> (C) -> (
-	  R := ring C;
-	  Hom(C,R^1))
+dual ChainComplex := ChainComplex => options Hom >> o -> C -> Hom(C, module ring C, o)
 
 Hom(ChainComplexMap, Module) := ChainComplexMap => opts -> (f, N) -> (
      complete f;

M2/Macaulay2/m2/matrix1.m2

@@ -605,7 +605,7 @@ Hom(Matrix, Module) := Matrix => o -> (f, N) -> inducedMap(Hom(source f, N, o),
 Hom(Module, Matrix) := Matrix => o -> (M, g) -> inducedMap(Hom(M, target g, o), Hom(M, source g, o), dual      cover M ** g, Verify => false)
 Hom(Matrix, Matrix) := Matrix => o -> (f, g) -> Hom(source f, g, o) * Hom(f, source g, o)
 
-dual Matrix := Matrix => {} >> o -> f -> Hom(f, module ring f)
+dual Matrix := Matrix => options Hom >> o -> f -> Hom(f, module ring f, o)
 
 -----------------------------------------------------------------------------
 

M2/Macaulay2/m2/modules2.m2

@@ -248,6 +248,7 @@ factor Module := opts -> (M) -> (
 
 -----------------------------------------------------------------------------
 
+-- TODO: compare speed with Hom(M, R^1)
 dual Module := Module => {} >> o -> F -> if F.cache.?dual then F.cache.dual else F.cache.dual = (
      if not isFreeModule F then kernel transpose presentation F
      else new Module from (ring F,rawDual raw F))