convert from param dictionary to list
    param_struct: structure of parameter array

def param_list_to_dict(list,param_struct,skeys):
    """convert from param dictionary to list
    param_struct: structure of parameter array
    """
    RV = []
    i0= 0
    for key in skeys:
        val = param_struct[key]
        shape = SP.array(val)
        np = shape.prod()
        i1 = i0+np
        params = list[i0:i1].reshape(shape)
        RV.append((key,params))
        i0 = i1
    return dict(RV)