[blackhole]

If you have an equation in your program that can be effectively simplified, you should have simplified it before writing in the first place. The thing about equations that can be simplified is that 99.9% of the time, they can be simplified at compile time.

If you want to write a library to do it for you, great! But don't advertise it as a replacement for floating point number representations, because it isn't.

[stiff]

Hey, why have compilers, if you can just write hand-optimized assembly yourself!

Compilers aren't able to do similar optimizations, first of all the flow of data that finally leads to some computation might be non-trivial and I think most compilers deal well only with reasonably local (in space and in time) optimizations. Besides, compilers typically don't know much mathematics. If I have a function for taking a square root and a function for squaring the compiler most likely wont rewrite sqr(sqrt(x)) to just x. Certainly it wont rearrange a quadratic equation to minimize round-off.

You are basically totally dismissing an idea on very little evidence, which is typical of HN lately. It certainly isn't completely hopeless and trying it out will shed much more light on the problem than your know-it-all-in-advance comments not substantiated by any evidence (like the claim about not being able to simplify most expressions and now the claim of 99.9%).

[ealloc]

He want more than compile-time simplification. He wants runtime simplification depending on the values encountered at runtime. For example in the quadratic equation.

And, he clearly isn't marketing it as a replacement for floating point. He says: "It is important to note, however, that the goal of the project is to make tools for symbolic calculations, not to create a viable alternative to the floating point." and he talks a lot about estimating numerical error and precision.

[stiff]

He says this about SymPy...

[ealloc]

oops you're right. Nevertheless, he clearly intends to extend rather than replace floating point since one of the goals is to estimate the errors in the floating point calculations, and he rounds.