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Port hamilton.cljc from scmutils #503
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added 13 commits
March 23, 2022 08:56
Codecov Report
@@ Coverage Diff @@
## main #503 +/- ##
==========================================
- Coverage 86.67% 86.54% -0.13%
==========================================
Files 103 104 +1
Lines 14751 14981 +230
Branches 776 779 +3
==========================================
+ Hits 12786 12966 +180
- Misses 1189 1236 +47
- Partials 776 779 +3
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added 13 commits
March 24, 2022 20:47
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Port hamilton.cljc from scmutils #503:
Changes the default implementation of
squareandcubefor differentialsto use
(expt <> 2)etc instead of(* <> <>).This is a big deal! For certain expressions there's a huge blowup when you
square a big symbolic term, and taking the derivative of it TWICE is very
messy.
With this change, differentials use the chain rule to calculuate the$x^2$ as $2x*x'$ , instead of using the product rule and$xx' + x'x$ .
derivative of
achieving a SECOND differentiatation of the same form and another
multiplication:
Before a judicious
simplifycall I added, this change dropped the runtimeof the
sicmutils.sicm.ch3-testsuite down by 6x. After the simplify changein
sicmutils.examples.topthe tests were still 40% faster in thatnamespace.
Fixes a bug where the
RationalFunctioncube implementation actually calledsquare.adds
sicmutils.mechanics.lagrange/Lagrangianfor building functionsignatures of Lagrangians.
adds the
sicmutils.mechanics.time-evolutionnamespaceadds
sicmutils.mechanics.lagrange/L-axisymmetric-top, more efficient thanthe version in
sicmutils.examples.topFleshes out
sicmutils.mechanics.hamilton:New functions:
H-state?,compatible-H-state?,state->p,momenta,P,literal-Hamiltonian-state,L-state->H-state,H-state->L-state,H-state->matrix,matrix->H-state,make-Hamiltonian,D-phase-space,Hamiltonian->Lagrangian-procedure,Hamiltonian->Lagrangian,flow-derivative,flow-transform,standard-map-inverse,F->K,J-func,T-func,canonical-H?,canonical-K?,linear-function->multiplier,Phi,Phi*,qp-canonical?,polar-canonical-inverse,two-particle-center-of-mass,two-particle-center-of-mass-canonical,transpose-function,multiplicative-transpose,symplectic-two-form,canonical-transform?,J-matrix,symplectic?F->CHmoves toF->CT(F->CTis now an alias)Legendre-transform-fnbecomesLegendre-transform-procedureand gainsmore correctness tests, toggled on and off by the
*validate-Legendre-transform?*dynamic variable.