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Diffstat (limited to 'math/aarch64/advsimd/tanpi.c')
| -rw-r--r-- | math/aarch64/advsimd/tanpi.c | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/math/aarch64/advsimd/tanpi.c b/math/aarch64/advsimd/tanpi.c new file mode 100644 index 000000000000..16de00ad5556 --- /dev/null +++ b/math/aarch64/advsimd/tanpi.c @@ -0,0 +1,88 @@ +/* + * Double-precision vector tanpi(x) function. + * + * Copyright (c) 2024, Arm Limited. + * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception + */ + +#include "v_math.h" +#include "test_sig.h" +#include "test_defs.h" + +const static struct v_tanpi_data +{ + float64x2_t c0, c2, c4, c6, c8, c10, c12; + double c1, c3, c5, c7, c9, c11, c13, c14; +} tanpi_data = { + /* Coefficents for tan(pi * x) computed with fpminimax + on [ 0x1p-1022 0x1p-2 ] + approx rel error: 0x1.7eap-55 + approx abs error: 0x1.7eap-55. */ + .c0 = V2 (0x1.921fb54442d18p1), /* pi. */ + .c1 = 0x1.4abbce625be52p3, .c2 = V2 (0x1.466bc6775b0f9p5), + .c3 = 0x1.45fff9b426f5ep7, .c4 = V2 (0x1.45f4730dbca5cp9), + .c5 = 0x1.45f3265994f85p11, .c6 = V2 (0x1.45f4234b330cap13), + .c7 = 0x1.45dca11be79ebp15, .c8 = V2 (0x1.47283fc5eea69p17), + .c9 = 0x1.3a6d958cdefaep19, .c10 = V2 (0x1.927896baee627p21), + .c11 = -0x1.89333f6acd922p19, .c12 = V2 (0x1.5d4e912bb8456p27), + .c13 = -0x1.a854d53ab6874p29, .c14 = 0x1.1b76de7681424p32, +}; + +/* Approximation for double-precision vector tanpi(x) + The maximum error is 3.06 ULP: + _ZGVnN2v_tanpi(0x1.0a4a07dfcca3ep-1) got -0x1.fa30112702c98p+3 + want -0x1.fa30112702c95p+3. */ +float64x2_t VPCS_ATTR V_NAME_D1 (tanpi) (float64x2_t x) +{ + const struct v_tanpi_data *d = ptr_barrier (&tanpi_data); + + float64x2_t n = vrndnq_f64 (x); + + /* inf produces nan that propagates. */ + float64x2_t xr = vsubq_f64 (x, n); + float64x2_t ar = vabdq_f64 (x, n); + uint64x2_t flip = vcgtq_f64 (ar, v_f64 (0.25)); + float64x2_t r = vbslq_f64 (flip, vsubq_f64 (v_f64 (0.5), ar), ar); + + /* Order-14 pairwise Horner. */ + float64x2_t r2 = vmulq_f64 (r, r); + float64x2_t r4 = vmulq_f64 (r2, r2); + + float64x2_t c_1_3 = vld1q_f64 (&d->c1); + float64x2_t c_5_7 = vld1q_f64 (&d->c5); + float64x2_t c_9_11 = vld1q_f64 (&d->c9); + float64x2_t c_13_14 = vld1q_f64 (&d->c13); + float64x2_t p01 = vfmaq_laneq_f64 (d->c0, r2, c_1_3, 0); + float64x2_t p23 = vfmaq_laneq_f64 (d->c2, r2, c_1_3, 1); + float64x2_t p45 = vfmaq_laneq_f64 (d->c4, r2, c_5_7, 0); + float64x2_t p67 = vfmaq_laneq_f64 (d->c6, r2, c_5_7, 1); + float64x2_t p89 = vfmaq_laneq_f64 (d->c8, r2, c_9_11, 0); + float64x2_t p1011 = vfmaq_laneq_f64 (d->c10, r2, c_9_11, 1); + float64x2_t p1213 = vfmaq_laneq_f64 (d->c12, r2, c_13_14, 0); + + float64x2_t p = vfmaq_laneq_f64 (p1213, r4, c_13_14, 1); + p = vfmaq_f64 (p1011, r4, p); + p = vfmaq_f64 (p89, r4, p); + p = vfmaq_f64 (p67, r4, p); + p = vfmaq_f64 (p45, r4, p); + p = vfmaq_f64 (p23, r4, p); + p = vfmaq_f64 (p01, r4, p); + p = vmulq_f64 (r, p); + + float64x2_t p_recip = vdivq_f64 (v_f64 (1.0), p); + float64x2_t y = vbslq_f64 (flip, p_recip, p); + + uint64x2_t sign + = veorq_u64 (vreinterpretq_u64_f64 (xr), vreinterpretq_u64_f64 (ar)); + return vreinterpretq_f64_u64 (vorrq_u64 (vreinterpretq_u64_f64 (y), sign)); +} + +#if WANT_TRIGPI_TESTS +TEST_DISABLE_FENV (V_NAME_D1 (tanpi)) +TEST_ULP (V_NAME_D1 (tanpi), 2.57) +TEST_SYM_INTERVAL (V_NAME_D1 (tanpi), 0, 0x1p-31, 50000) +TEST_SYM_INTERVAL (V_NAME_D1 (tanpi), 0x1p-31, 0.5, 50000) +TEST_SYM_INTERVAL (V_NAME_D1 (tanpi), 0.5, 1.0, 200000) +TEST_SYM_INTERVAL (V_NAME_D1 (tanpi), 1.0, 0x1p23, 50000) +TEST_SYM_INTERVAL (V_NAME_D1 (tanpi), 0x1p23, inf, 50000) +#endif |