bpms.c

// gcc -o bpms bpms.c -Wall && ./bpms
#include<stdio.h>

int main (int argc, char** argv)
{
	// 176400: 2 2 2 2 3 3 5 5 7 7          == 2^4  * 3^2 * 5^2 * 7^2
	// 384000: 2 2 2 2 2 2 2 2 2 2 3 5 5 5  == 2^10 * 3^1 * 5^3

	int sr = 56448000; // 2^10 * 3^2 * 5^3 * 7^2
	int i  = 0;

	double pbpm = 0;
	double dmax = 0;
	double bmax = 0;

	while (1) {
		// assume shortest note is a 128th
		double bpm = 60.0/128.0 * sr / ++i;

		if (bpm > 400) {
			pbpm = bpm;
			continue;
		}

		double diff = pbpm - bpm;
		if (diff > dmax) {
			dmax = diff;
			bmax = bpm;
		}

		pbpm = bpm;

		if (bpm < 20) {
			printf ("Min delta at %6.2f: %f\n", bpm, diff);
			break;
		}
	}
	printf ("Max delta at %6.2f: %f\n", bmax, dmax);
	return 0;
}