compiler-construction - Derivative Code Compilers

Question

I would like to ask if some one can explain to me what are the differences of syntax-directed tangent-linear code and adjoint code.

It is related to derivation of code with a compiler.

I understand that they are different ways to make the derivations of the mathematical equations in a program, but, I don't know exactly how to interpret them.

Thanks in advance.

Regards.

Answer 1

据我了解，自动创建衍生代码只有两种方法：

• 前向分化
• 后向分化

据我了解，向后微分只是学术性的，因为它需要记住在数组中执行的操作，最后返回这个数组并解释这个数组的内容。结果（由于解释）这样的代码非常慢。

据我记得，后退方法与链式法则有关。

也可以混合使用两种方法：如果您有一段代码：

    a=f(b);

并且函数 f() 不是微不足道的，并且 b 带有许多导数，那么它有助于计算

    a=f(b);
    da_db=df(b);
    da_dc=da_db*db_dc;
    da_dd=da_db*db_dd;