fastapprox

Rust版本的Paul Mineiro的库。

机器学习中出现的一些函数的快速近似版本。

例如，在Vowpal Wabbit中，这是实现其惊人的训练速度的许多巧妙技巧之一。

模块名称 fast 和 faster 来自原始工作，代表具有不同速度-精度级别的相同算法集合。

虽然近似函数可能会给你一些加速（但不一定是！），应该提供一些警告

• 运行自己的基准测试
• 确保数学是算法中的瓶颈
• 注意收敛性
• SIMD版本尚未实现（直到simd crate从孵化器毕业）

基准测试

在MacBook Pro（2013年晚期），2.6 GHz Intel Core i7上运行cargo bench给出以下输出

test cos_fast            ... bench:       3,674 ns/iter (+/- 778)
test cos_faster          ... bench:       1,559 ns/iter (+/- 206)
test cos_std             ... bench:       7,329 ns/iter (+/- 104)
test cosfull_fast        ... bench:       6,880 ns/iter (+/- 1,021)
test cosfull_faster      ... bench:       4,238 ns/iter (+/- 183)
test cosh_fast           ... bench:       8,270 ns/iter (+/- 4,190)
test cosh_faster         ... bench:       2,451 ns/iter (+/- 175)
test cosh_std            ... bench:       4,407 ns/iter (+/- 798)
test digamma_fast        ... bench:       4,644 ns/iter (+/- 1,126)
test digamma_faster      ... bench:       3,770 ns/iter (+/- 417)
test digamma_special     ... bench:      16,260 ns/iter (+/- 1,374)
test digamma_statrs      ... bench:      14,401 ns/iter (+/- 3,198)
test erf_fast            ... bench:      54,401 ns/iter (+/- 20,448)
test erf_faster          ... bench:       2,359 ns/iter (+/- 426)
test erf_inv_fast        ... bench:       5,958 ns/iter (+/- 2,794)
test erf_inv_faster      ... bench:       2,113 ns/iter (+/- 153)
test erf_inv_statrs      ... bench:         769 ns/iter (+/- 83)
test erf_special         ... bench:       4,948 ns/iter (+/- 1,443)
test erf_statrs          ... bench:       6,287 ns/iter (+/- 246)
test erfc_fast           ... bench:      54,201 ns/iter (+/- 6,307)
test erfc_faster         ... bench:       2,052 ns/iter (+/- 112)
test erfc_special        ... bench:       4,887 ns/iter (+/- 362)
test exp_fast            ... bench:       3,774 ns/iter (+/- 235)
test exp_faster          ... bench:       1,400 ns/iter (+/- 260)
test exp_std             ... bench:       2,760 ns/iter (+/- 202)
test lambertw_fast       ... bench:      21,040 ns/iter (+/- 2,523)
test lambertw_faster     ... bench:      24,840 ns/iter (+/- 8,939)
test lambertwexpx_fast   ... bench:      13,240 ns/iter (+/- 858)
test lambertwexpx_faster ... bench:       8,857 ns/iter (+/- 1,439)
test ln_fast             ... bench:       2,087 ns/iter (+/- 528)
test ln_faster           ... bench:       1,214 ns/iter (+/- 447)
test ln_gamma_fast       ... bench:       6,193 ns/iter (+/- 901)
test ln_gamma_faster     ... bench:       2,952 ns/iter (+/- 211)
test ln_gamma_special    ... bench:      36,726 ns/iter (+/- 846)
test ln_gamma_statrs     ... bench:      56,295 ns/iter (+/- 973)
test ln_std              ... bench:       5,175 ns/iter (+/- 321)
test log2_fast           ... bench:       1,998 ns/iter (+/- 335)
test log2_faster         ... bench:       1,206 ns/iter (+/- 188)
test log2_std            ... bench:       5,087 ns/iter (+/- 1,736)
test pow2_fast           ... bench:       3,472 ns/iter (+/- 192)
test pow2_faster         ... bench:       1,069 ns/iter (+/- 356)
test pow2_std            ... bench:       2,942 ns/iter (+/- 172)
test pow_fast            ... bench:       6,769 ns/iter (+/- 1,460)
test pow_faster          ... bench:       2,365 ns/iter (+/- 293)
test pow_std             ... bench:      13,147 ns/iter (+/- 1,000)
test sigmoid_fast        ... bench:       4,818 ns/iter (+/- 428)
test sigmoid_faster      ... bench:       1,869 ns/iter (+/- 56)
test sigmoid_std         ... bench:       3,312 ns/iter (+/- 131)
test sin_fast            ... bench:       3,038 ns/iter (+/- 685)
test sin_faster          ... bench:       1,875 ns/iter (+/- 481)
test sin_std             ... bench:       7,215 ns/iter (+/- 39)
test sinfull_fast        ... bench:       6,483 ns/iter (+/- 405)
test sinfull_faster      ... bench:       3,973 ns/iter (+/- 874)
test sinh_fast           ... bench:       8,394 ns/iter (+/- 618)
test sinh_faster         ... bench:       2,588 ns/iter (+/- 286)
test sinh_std            ... bench:       4,434 ns/iter (+/- 329)
test tan_fast            ... bench:       5,165 ns/iter (+/- 174)
test tan_faster          ... bench:       3,423 ns/iter (+/- 1,083)
test tan_std             ... bench:       7,695 ns/iter (+/- 453)
test tanfull_fast        ... bench:      10,299 ns/iter (+/- 1,761)
test tanfull_faster      ... bench:       6,214 ns/iter (+/- 524)
test tanh_fast           ... bench:       5,598 ns/iter (+/- 709)
test tanh_faster         ... bench:       1,921 ns/iter (+/- 445)
test tanh_std            ... bench:       4,056 ns/iter (+/- 306)