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Root mean square (RMS) — v0.0.6-alpha.1

The pure builtin rms(values: vector) -> float first shipped in v0.0.6-alpha.1 (source aa329a22cf2bf92d2c9814a26ff9c8b67a72e6e8). Earlier alpha.5 binaries do not have it.

For a nonempty vector of finite values, RMS is the square root of the mean of the squared elements. It measures magnitude without depending on the signs of those elements. Internally the implementation scales first and uses compensated accumulation: it does not directly square huge inputs and overflow. Results are rounded binary64 approximations.

Run the exact published example

Full source from examples/root_mean_square.srp:

// RMS measures signal magnitude without forming an overflowing norm.
bind signal = [3.0, 4.0];
print(rms(signal) > 3.5, rms(signal) < 3.6);
print(rms([2.0, -2.0]));
print(rms(window([99.0, 3.0, 4.0, 99.0], 1, 2)) == rms(signal));
print(rms([1e308, -1e308]) == 1e308);
print(rms([0.0, -0.0]));

Exact expected stdout:

true true
2.0
true
true
0.0

From the tagged source's root:

scarp verify examples/root_mean_square.srp
scarp exec examples/root_mean_square.srp

The window example reads only the visible slice. An all-zero vector returns positive 0.0; extreme finite inputs remain finite. Equality in this specific example is verified by the compiler's fixture, but general floating-point comparisons should use tolerances.

Domain, type, work and memory boundaries

  • An empty vector such as rms([]) reports E0034 at its argument.
  • Wrong argument types/arity use the existing type and argument diagnostics; there is no automatic conversion from the integer collection type.
  • The kernel prepays 4n native work steps for n visible items. Other program work still costs steps.
  • RMS allocates no additional numerical payload. Creating the original vector still counts against allocation limits; a vector has at most 65,536 visible elements.
  • verify checks types without evaluating the runtime numerical domain. Errors discard buffered output under the interpreter's normal atomic-output rules.
  • The experimental scalar C11 Rust API does not support RMS or vector code generation; unsupported expressions report E0049.

The exact compiler specification documents numerical edge cases, and alpha.6 release notes explain the version boundary.

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