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jordens merged 1 commit into from
Feb 11, 2026
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README: add some performance numbers #49

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6 changes: 3 additions & 3 deletions README.md
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Expand Up @@ -15,11 +15,11 @@ One comprehensive user for these algorithms is [Stabilizer](https://github.com/q

### Cosine/Sine

[`cossin()`] uses a small (128 element or 512 byte) LUT, smart octant (un)mapping, linear interpolation and comprehensive analysis of corner cases to achieve a very clean signal (4e-6 RMS error, 9e-6 max error, 108 dB SNR typ), low spurs, and no bias with about 40 cortex-m instruction per call. It computes both cosine and sine (i.e. the complex signal) at once given a phase input.
[`cossin()`] uses a small (128 element or 512 byte) LUT, smart octant (un)mapping, linear interpolation and comprehensive analysis of corner cases to achieve a very clean signal (4e-6 RMS error, 9e-6 max error, 108 dB SNR typ), low spurs, and no bias with about 40 cortex-m instructions per call (23.5 cycles on Cortex-M7, see `tests/embedded`). It computes both cosine and sine (i.e. the complex signal) at once given a phase input.

### Two-argument arcus-tangens

[`atan2()`] returns a phase given a complex signal (a pair of in-phase/`x`/cosine and quadrature/`y`/sine). The RMS phase error is less than 5e-6 rad, max error is less than 1.2e-5 rad, i.e. 20.5 bit RMS, 19.1 bit max accuracy. The bias is minimal.
[`atan2()`] returns a phase given a complex signal (a pair of in-phase/`x`/cosine and quadrature/`y`/sine). The RMS phase error is less than 5e-6 rad, max error is less than 1.2e-5 rad, i.e. 20.5 bit RMS, 19.1 bit max accuracy. The bias is minimal. It takes about 60 cycles on Cortex-M7 (see `tests/embedded`).

### CORDIC

Expand Down Expand Up @@ -73,7 +73,7 @@ TL;DR: `idsp` is as fast and offers more features.
| Support for fixed point `a1=-2` second order integrator | ❌ | ❌ | ✅ |

The benchmarks and results comparing `idsp` and `biquad-rs` are in `tests/embedded`.
`idsp`'s biquad can process one `i32` sample every 8.5 cycles and one `f32` sample every 12 cycles on a cortex-m7.
`idsp`'s biquad can process one `i32` sample every 8.5 cycles and one `f32` sample every 12 cycles on a Cortex-M7.

## State variable, normal form, wave digital filter

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