You can't have calculus without the real numbers, and you can't have asymptotic analysis and probability theory without calculus. There goes the whole field of the analysis of algorithms.
You can do discrete math
(including analysis of algorithms) without reals.
Reals are only needed for calculus on infintesimals, which are not relevant to much of CS. Everything you can do with formal Taylor expansions doesn't need reals. In fact knowing calculus on the reals often causes confusion in students learning formal expansions for CS.
Reals are only needed for calculus on infintesimals, which are not relevant to much of CS. Everything you can do with formal Taylor expansions doesn't need reals. In fact knowing calculus on the reals often causes confusion in students learning formal expansions for CS.