derive

fun <R> derive(value: R, block: F.(R) -> Unit): R

Performs update of derivative after the rest of the formula in the back-pass.

For example, implementation of sin function is:

fun AD.sin(x: Variable): Variable = derive(Variable(sin(x.x)) { z -> // call derive with function result
    x.d += z.d * cos(x.x) // update derivative using chain rule and derivative of the function
}

Sources

common source