decimal_util

ソースコード

from titan_pylib.math.decimal_util import decimal_pi
from titan_pylib.math.decimal_util import decimal_exp
from titan_pylib.math.decimal_util import decimal_cos
from titan_pylib.math.decimal_util import decimal_sin
from titan_pylib.math.decimal_util import decimal_asin
from titan_pylib.math.decimal_util import decimal_acos

view on github

展開済みコード

  1# 展開に失敗しました
  2from decimal import Decimal, getcontext
  3import math
  4
  5
  6def decimal_pi() -> Decimal:
  7    getcontext().prec += 2
  8    three = Decimal(3)
  9    lasts, t, s, n, na, d, da = 0, three, 3, 1, 0, 0, 24
 10    while s != lasts:
 11        lasts = s
 12        n, na = n + na, na + 8
 13        d, da = d + da, da + 32
 14        t = (t * n) / d
 15        s += t
 16    getcontext().prec -= 2
 17    return +s
 18
 19
 20def decimal_exp(x: Decimal) -> Decimal:
 21    getcontext().prec += 2
 22    i, lasts, s, fact, num = 0, 0, 1, 1, 1
 23    while s != lasts:
 24        lasts = s
 25        i += 1
 26        fact *= i
 27        num *= x
 28        s += num / fact
 29    getcontext().prec -= 2
 30    return +s
 31
 32
 33def decimal_cos(x: Decimal) -> Decimal:
 34    getcontext().prec += 2
 35    i, lasts, s, fact, num, sign = 0, 0, 1, 1, 1, 1
 36    while s != lasts:
 37        lasts = s
 38        i += 2
 39        fact *= i * (i - 1)
 40        num *= x * x
 41        sign *= -1
 42        s += num / fact * sign
 43    getcontext().prec -= 2
 44    return +s
 45
 46
 47def decimal_sin(x: Decimal) -> Decimal:
 48    getcontext().prec += 2
 49    i, lasts, s, fact, num, sign = 1, 0, x, 1, x, 1
 50    while s != lasts:
 51        lasts = s
 52        i += 2
 53        fact *= i * (i - 1)
 54        num *= x * x
 55        sign *= -1
 56        s += num / fact * sign
 57    getcontext().prec -= 2
 58    return +s
 59
 60
 61def decimal_asin(x: Decimal) -> Decimal:
 62    assert isinstance(x, Decimal)
 63    if x < -1 or x > 1:
 64        raise ValueError("math domain error")
 65    if x == 1:
 66        return decimal_pi() / 2
 67    if x == -1:
 68        return -decimal_pi() / 2
 69    getcontext().prec += 2
 70    eps = Decimal("1e-" + str(getcontext().prec))
 71    sum_acos = x
 72    term = Decimal(1)
 73    power = x
 74    n = 0
 75    while abs(term * power) > eps:
 76        n += 1
 77        term *= (2 * n - 1) * (2 * n) * (2 * (n - 1) + 1)
 78        term /= 4 * n * n * (2 * n + 1)
 79        power *= x * x
 80        sum_acos += term * power
 81    result = sum_acos
 82    getcontext().prec -= 2
 83    return +result
 84
 85
 86def decimal_acos(x: Decimal) -> Decimal:
 87    assert isinstance(x, Decimal)
 88    if x < -1 or x > 1:
 89        raise ValueError("math domain error")
 90    if x == 1:
 91        return Decimal(0)
 92    if x == -1:
 93        return decimal_pi()
 94    getcontext().prec += 2
 95    eps = Decimal("1e-" + str(getcontext().prec))
 96    sum_acos = x
 97    term = Decimal(1)
 98    power = x
 99    n = 0
100    while abs(term * power) > eps:
101        n += 1
102        term *= (2 * n - 1) * (2 * n) * (2 * (n - 1) + 1)
103        term /= 4 * n * n * (2 * n + 1)
104        power *= x * x
105        sum_acos += term * power
106    result = decimal_pi() / 2 - sum_acos
107    getcontext().prec -= 2
108    return +result

仕様

decimal_acos(x: Decimal) → Decimal[source]
decimal_asin(x: Decimal) → Decimal[source]
decimal_cos(x: Decimal) → Decimal[source]
decimal_exp(x: Decimal) → Decimal[source]
decimal_pi() → Decimal[source]
decimal_sin(x: Decimal) → Decimal[source]