How to apply TDD with complicated function?

Uncle Bob's three rules of test-driven development state the following:

1. You are not allowed to write any production code unless it is to make a failing unit test pass.

2. You are not allowed to write any more of a unit test than is sufficient to fail; and compilation failures are failures.

3. You are not allowed to write any more production code than is sufficient to pass the one failing unit test.

In real world, for example, I have a task to complete a method which requires some complex algorithms (some advanced math knowledge for example), if I apply 3 above rules, it will be like this:

• start writing a test case => run and see it fails

• write lines of code that just enough to make the test pass

• refactor the code

• then repeat this loop.

My question is: is this approach quite unrealistic and distracted in such situations? Why don't we write the first test case, then focus on finding the solution then implement it, I mean looking at the big picture, instead of writing just enough code to pass the first test case?

(I am a new with TDD)