29 lines
718 B
Plaintext
29 lines
718 B
Plaintext
// polynomial for approximating asinh(x)
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//
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// Copyright (c) 2022-2023, Arm Limited.
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// SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
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// Polynomial is used in [2^-26, 1]. However it is least accurate close to 1, so
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// we use 2^-6 as the lower bound for coeff generation, which yields sufficiently
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// accurate results in [2^-26, 2^-6].
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a = 0x1p-6;
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b = 1.0;
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f = (asinh(sqrt(x)) - sqrt(x))/x^(3/2);
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approx = proc(poly, d) {
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return remez(1 - poly(x)/f(x), deg-d, [a;b], x^d/f(x), 1e-10);
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};
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poly = 0;
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for i from 0 to deg do {
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i;
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p = roundcoefficients(approx(poly,i), [|D ...|]);
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poly = poly + x^i*coeff(p,0);
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};
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display = hexadecimal;
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print("coeffs:");
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for i from 0 to deg do coeff(poly,i);
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