[Extend] Add maxima script for state evolution

src/state/calculation.wxm

+/* [wxMaxima batch file version 1] [ DO NOT EDIT BY HAND! ]*/
+/* [ Created with wxMaxima version 12.04.0 ] */
+
+/* [wxMaxima: input   start ] */
+d_eq    : 'diff(theta,t) = 1 - theta*(V/L);
+  ode2(d_eq, theta, t)$
+  subst(L/V[ref]*exp(alpha), theta, %)$
+  % / L * V[ref]$
+  ic1(%, t = 0, alpha = alpha[0])$
+d_alpha : log(expand(%));
+/* [wxMaxima: input   end   ] */
+
+/* [wxMaxima: input   start ] */
+r_eq : 'diff(theta,t) = -(V/L)*theta*log(theta*(V/L));
+  ode2(r_eq,theta,t)$
+  subst(L/V[ref] * exp(alpha),theta,%)$
+  ic1(%,t=0,alpha=alpha[0])$
+  map(exp,-(V/L)*%)$
+  block([logexpand : all], expand(% - log(V/V[ref])))$
+r_alpha : expand(logcontract(%));
+/* [wxMaxima: input   end   ] */
+
+/* Maxima can't load/batch files which end with a comment! */
+"Created with wxMaxima"$