Gets the best resistors in the E12 series to use for a particular voltage drop desired

voltage_divider.py

E12 = (1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2)
ROS = tuple((x / y, (x, y)) for x in E12 for y in E12)


def estimator(inv, ouv):
    ratio = (inv - ouv) / ouv
    for r, v in ROS:
        abserr = abs(r - ratio)
        relerr = abserr / ratio
        yield (relerr, abserr, v)

if __name__ == "__main__":
    inv = 8.4
    ouv = 5.0
    for a, b, r in sorted(estimator(inv, ouv))[:5]:
    	print(r, "- Ratio: %.5f, Error: %.2f%%" % (r[0] / r[1], a * 100))
	    print("\t%.2f => %.5f" % (inv, (inv * r[1]) / (r[0] + r[1])))