dist -- produces a DiffAlgDistribution from a list

i1 : X = newField("3*x_0*ax_0+x_1*ax_1")

o1 = 3x ax  + x ax
       0  0    1  1

o1 : DiffAlgField

i2 : Y = radial 3

o2 = x ax  + x ax  + x ax  + x ax
      0  0    1  1    2  2    3  3

o2 : DiffAlgField

i3 : dist {X,Y}

o3 = {3x ax  + x ax , x ax  + x ax  + x ax  + x ax }
        0  0    1  1   0  0    1  1    2  2    3  3

o3 : DiffAlgDistribution