如果MATLAB自带的工具箱不好使，你最好考虑自己造轮子

Dear Xiao,

Mathematica does solve DDEs... I cannot see where is the problem with your equations to be solved in Mathematica TBH...

https://reference.wolfram.com/language/tutorial/NDSolveDelayDifferentialEquations.html

Kind regards,

Julian

J. Anaya Dear Julian,

Thanks for your reply.

Mathematica's documentation says that " Currently, the implementation for DDEs in NDSolve only supports constant delays"...

however, in my case, the delays follows a harmonic motion, which is something like A*sin(\omega t).

Your picture shows an implicit ODE. Try the FortranCalculus (FC) language that got its start by NASA's Apollo Space program.

FC-Compiler™ application is a (free) Calculus-level Compiler that simplifies Tweaking parameters in ones math model. FC solves Algebraic through Ordinary Differential Equations Equations; Laplace transforms; etc. FC is based on Automatic Differentiation that simplifies computer code to an absolute minimum; i.e., a mathematical model, constraints, and the objective (function) definition.

Most math Modeling, Simulations, & Optimizations can be easily solved with a Calculus-level language/compiler. A half-hour per problem should be enough time to code and execute most math problems. Solves Algebraic Equations through Ordinary Differential Equations, for more visit http://fortrancalculus.info/apps/fc-compiler.html . Equations may be implicit, non-linear, Boundary Value Problems (BVP), Initial Value Problems (IVP), etc. Download, install, & execute some demo problems. Simple and its Freeware! (PDE solvers are in the works!)