Is there some way with a Printf format string to say this: Printf.sprintf "%03d_%03d_%03d" millions thousands units But, without having to compute millions, thousands and units (as I naively implemented)? I.e. I would like to have a ‘_’ to separate every three digits starting from the right.

[image] UnixJunkie: Is there some way with a Printf format string to say this: Yes, it is documented in the manual: Printf.sprintf "%#d". Cheers, Nicolas

Indeed: OCaml library : Printf d, i: convert an integer argument to signed decimal. The flag # adds underscores to large values for readability. I never spotted it in the manual; probably because there is not the keywork “financial”.

I didn’t know this ! It’s a pity it doesn’t work for floats.

Same, it’s cool. However floats also have their own hidden gem, for those who don’t know: exact printing in hexadecimal! # Printf.printf "%h\n" 42.1;; 0x1.50ccccccccccdp+5 If only this was supported in more languages…

[image] c-cube: If only this was supported in more languages… This was already specified in C99 with the format specifier %a, some 15 years before OCaml’s implementation… Cheers, Nicolas

See also: Decimal floating point arithmetic Fixed Point Arithmetic support - language design - Rust Internals Fixed-point number support? · Issue #1974 · ziglang/zig · GitHub fixed - Rust https://crates.io/crates/decimal/ https://crates.io/crates/rust-decimal https://crates.io/crates/bigdecimal H…

We do have something like this in OCaml :slight_smile: bigdecimal v0.16.0 (latest) · OCaml Package decimal 0.4.0 (latest) · OCaml Package

I wonder if fixed point arithmetic would go significantly faster than regular floats. I wonder if this would be useful for scientific calculations (like Molecular Dynamics). Cc @scemama

A very good reference for throughput and latencies of CPU instructions is this document: instruction_tables.pdf 2.09 MB Based on this data, I would say that in the general case (64 bits) it would be slower: Integer division usually takes more cycles than fl…

Kind of "financial" integer printing format

Learning

yawaramin June 27, 2023, 5:03am 8

We do have something like this in OCaml

bigdecimal v0.16.0 (latest) · OCaml Package
decimal 0.4.0 (latest) · OCaml Package

Decimal floating point arithmetic

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