func (m *Mass) Adjust(newmass Real) {
C.dMassAdjust((*C.dMass)(m), C.dReal(newmass))
}
// Adjust sets parameters based on the given total mass.
func (m *Mass) Adjust(mass float64) {
c := &C.dMass{}
m.toC(c)
C.dMassAdjust(c, C.dReal(mass))
m.fromC(c)
}