[plt-scheme] best way to printf "%.2f" ?

Is there any reason why PLT Scheme doesn't support (extensible and 
built-in) C-style printf operations? This way more transformations like 
this could be easily achievable.

One thing I would also like (and recommend using instead of the 
scientific notation for anything engineering/physics related) is the 
engineering notation when the exponent is always divisible by 3. It 
optionally could be converted to unicode prefixes (T,M,k,,m,\mu,n,p). 
It's much easier to read and visualize than the classical scientific form.

-- 
regards,
Jakub Piotr Cłapa