kill(all)$

maxma :concept differentation with scale factors ,version 1.0
peter.vlasschaert@gmail.com,07/09/2021

load(lrats)$

pa:'diff(mm,sf*θθ)=1/sf*'diff(mm,θθ);

pa1:subst([sf=r],pa);

pa2:mm=k*da*rhs(pa1);

depends(mm,[θθ,r]);

pa3:subst([pa2],pa1);

rem : ev control both sides equation, isolate second part 'see :pa4'

pa4:rhs(pa3);

pa5:ev(pa4,diff);

pa6:lhs(pa3)=pa5;