linux-6.12.1/lib/polynomial.c

1 // SPDX-License-Identifier: GPL-2.0-only
18  * Originally this was part of drivers/hwmon/bt1-pvt.c.
22  * to PVT data and vice-versa are following:
24  * N = 1.8322e-8*(T^4) + 2.343e-5*(T^3) + 8.7018e-3*(T^2) + 3.9269*(T^1) +
26  * T = -1.6743e-11*(N^4) + 8.1542e-8*(N^3) + -1.8201e-4*(N^2) +
27  *     3.1020e-1*(N^1) - 4.838e1
29  * where T = [-48.380, 147.438]C and N = [0, 1023].
38  * N = (18322e-20*(T^4) + 2343e-13*(T^3) + 87018e-9*(T^2) + 39269e-3*T +
40  * T = -16743e-12*(D^4) + 81542e-9*(D^3) - 182010e-6*(D^2) + 310200e-3*D -
42  * where T = [-48380, 147438] mC and N = [0, 1023].
58  *                 {4, -16743, 1000, 1},
60  *                 {2, -182010, 1000, 1},
62  *                 {0, -48380, 1, 1}
68  * polynomial_calc - calculate a polynomial using integer arithmetic
79 long polynomial_calc(const struct polynomial *poly, long data)  in polynomial_calc()
81 	const struct polynomial_term *term = poly->terms;  in polynomial_calc()  local
82 	long total_divider = poly->total_divider ?: 1;  in polynomial_calc()
83 	long tmp, ret = 0;  in polynomial_calc()
89 	 * We walk over each degree term up to the free one, and perform  in polynomial_calc()
90 	 * the redistributed multiplication of the term coefficient, its  in polynomial_calc()
97 		tmp = term->coef;  in polynomial_calc()
98 		for (deg = 0; deg < term->deg; ++deg)  in polynomial_calc()
99 			tmp = mult_frac(tmp, data, term->divider);  in polynomial_calc()
100 		ret += tmp / term->divider_leftover;  in polynomial_calc()
101 	} while ((term++)->deg);  in polynomial_calc()