92 lines
2.6 KiB
TypeScript
92 lines
2.6 KiB
TypeScript
|
/**
|
|||
|
|
* Time-domain statistics for SPICE `.tran` waveforms.
|
|||
|
|
*
|
|||
|
|
* Used by instruments (voltmeter, ammeter, overlay) to display physically
|
|||
|
|
* meaningful AC values — RMS for "steady-state AC reading", peak for
|
|||
|
|
* "scope cursor", and DC component for the underlying bias.
|
|||
|
|
*
|
|||
|
|
* Also houses the linear interpolator used by the per-read ADC hook.
|
|||
|
|
*/
|
|||
|
|
|
|||
|
|
/** Root-mean-square: sqrt(mean(x²)). For a pure sine, Vpk/√2. */
|
|||
|
|
export function rms(samples: readonly number[]): number {
|
|||
|
|
if (samples.length === 0) return 0;
|
|||
|
|
let sumSq = 0;
|
|||
|
|
for (const s of samples) sumSq += s * s;
|
|||
|
|
return Math.sqrt(sumSq / samples.length);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/** Arithmetic mean (DC component). */
|
|||
|
|
export function mean(samples: readonly number[]): number {
|
|||
|
|
if (samples.length === 0) return 0;
|
|||
|
|
let sum = 0;
|
|||
|
|
for (const s of samples) sum += s;
|
|||
|
|
return sum / samples.length;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/** Maximum absolute value. */
|
|||
|
|
export function peak(samples: readonly number[]): number {
|
|||
|
|
let p = 0;
|
|||
|
|
for (const s of samples) {
|
|||
|
|
const a = Math.abs(s);
|
|||
|
|
if (a > p) p = a;
|
|||
|
|
}
|
|||
|
|
return p;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/** Max − min. */
|
|||
|
|
export function peakToPeak(samples: readonly number[]): number {
|
|||
|
|
if (samples.length === 0) return 0;
|
|||
|
|
let min = samples[0];
|
|||
|
|
let max = samples[0];
|
|||
|
|
for (let i = 1; i < samples.length; i++) {
|
|||
|
|
const s = samples[i];
|
|||
|
|
if (s < min) min = s;
|
|||
|
|
if (s > max) max = s;
|
|||
|
|
}
|
|||
|
|
return max - min;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/** True if the signal has any AC content above `epsilon` peak-to-peak. */
|
|||
|
|
export function isAC(samples: readonly number[], epsilon = 1e-4): boolean {
|
|||
|
|
return peakToPeak(samples) > epsilon;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/**
|
|||
|
|
* Element-wise difference of two waveforms sampled on the same time base.
|
|||
|
|
* If lengths differ, the shorter wins. Used by voltmeter (probe+ − probe−).
|
|||
|
|
*/
|
|||
|
|
export function subtract(a: readonly number[], b: readonly number[]): number[] {
|
|||
|
|
const n = Math.min(a.length, b.length);
|
|||
|
|
const out = new Array<number>(n);
|
|||
|
|
for (let i = 0; i < n; i++) out[i] = a[i] - b[i];
|
|||
|
|
return out;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/**
|
|||
|
|
* Linear interpolation across a (time, value) table. `ts` must be
|
|||
|
|
* monotonically increasing. Clamps to the endpoints if `t` is outside range.
|
|||
|
|
* O(log n) via binary search — safe to call at >1 kHz rates.
|
|||
|
|
*/
|
|||
|
|
export function interpolateAt(
|
|||
|
|
ts: readonly number[],
|
|||
|
|
vs: readonly number[],
|
|||
|
|
t: number,
|
|||
|
|
): number {
|
|||
|
|
if (ts.length === 0) return 0;
|
|||
|
|
if (t <= ts[0]) return vs[0];
|
|||
|
|
const lastIdx = ts.length - 1;
|
|||
|
|
if (t >= ts[lastIdx]) return vs[lastIdx];
|
|||
|
|
let lo = 0;
|
|||
|
|
let hi = lastIdx;
|
|||
|
|
while (lo + 1 < hi) {
|
|||
|
|
const mid = (lo + hi) >> 1;
|
|||
|
|
if (ts[mid] <= t) lo = mid; else hi = mid;
|
|||
|
|
}
|
|||
|
|
const t0 = ts[lo];
|
|||
|
|
const t1 = ts[hi];
|
|||
|
|
if (t1 === t0) return vs[lo];
|
|||
|
|
const a = (t - t0) / (t1 - t0);
|
|||
|
|
return vs[lo] * (1 - a) + vs[hi] * a;
|
|||
|
|
}
|