> The Spider Objects

>       TOY SPIRAL data generation object

>        A=spiral(H) returns a spiral toy data object initialized with hyperparameters H.

>        This generates 2 spirals with 4*m points per spiral, where 1*m points are
>        points on two perfect spiral and 3*m points are some additive noise on
>        the first quarter.

>        Hyperparameters, and their defaults
>         n=1           --  a parameter :-) play to explore
>         m=50          --  number of used points per winding

>        Model

>        Methods:
>         generate,train,test
>         Example :
>          d=gen(spiral({'n=1','m=50'}));
>          [r s0]=train(svm(kernel('rbf',1)),d)
>          plot(s0,[ -20 20 -20 20]);