Online Algebra Calculator
Many of users do not use powerful Maxima computer algebra system for systematic work, but for ad hoc algebraic calculations – equations, functions, matrixes, etc. only. To do this job, it is not useful to download the whole application from a web site.
Function: covdiff (<expr>, <v_1>, <v_2>, ...) Yields the covariant derivative of <expr> with respect to the variables <v_i> in terms of the Christoffel symbols of the second kind (ichr2). In order to evaluate these, one should use ev(<expr>,ichr2).
(%i1) load(itensor);
(%o1) /share/tensor/itensor.lisp
(%i2) entertensor()$
Enter tensor name: a;
Enter a list of the covariant indices: [i,j];
Enter a list of the contravariant indices: [k];
Enter a list of the derivative indices: [];
k
(%t2) a
i j
(%i3) ishow(covdiff(%,s))$
k %1 k %1 k
(%t3) - a ichr2 - a ichr2 + a
i %1 j s %1 j i s i j,sk %1 + ichr2 a %1 s i j
(%i4) imetric:g;
(%o4) g
(%i5) ishow(ev(%th(2),ichr2))$
%1 %4 k
g a (g - g + g )
i %1 s %4,j j s,%4 j %4,s
(%t5) - ------------------------------------------
2
%1 %3 k
g a (g - g + g )
%1 j s %3,i i s,%3 i %3,s
- ------------------------------------------
2
k %2 %1
g a (g - g + g )
i j s %2,%1 %1 s,%2 %1 %2,s k
+ ------------------------------------------- + a
2 i j,s
(%i6)
(%o1) true (%i2)