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author | Raymond Hettinger <python@rcn.com> | 2004-07-06 01:55:14 (GMT) |
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committer | Raymond Hettinger <python@rcn.com> | 2004-07-06 01:55:14 (GMT) |
commit | 2f55eb4ccad92efeb1d422c96aacd2cfa659c5c6 (patch) | |
tree | 31e8367f98541fa284495da75b8446288ff654b9 | |
parent | 0aeac107cadd1472e5ea109f7f29e6a6527ae1ec (diff) | |
download | cpython-2f55eb4ccad92efeb1d422c96aacd2cfa659c5c6.zip cpython-2f55eb4ccad92efeb1d422c96aacd2cfa659c5c6.tar.gz cpython-2f55eb4ccad92efeb1d422c96aacd2cfa659c5c6.tar.bz2 |
Demonstrate how to round final result.
-rw-r--r-- | Doc/lib/libdecimal.tex | 34 |
1 files changed, 17 insertions, 17 deletions
diff --git a/Doc/lib/libdecimal.tex b/Doc/lib/libdecimal.tex index 08c9b9e..66aad93 100644 --- a/Doc/lib/libdecimal.tex +++ b/Doc/lib/libdecimal.tex @@ -932,9 +932,9 @@ def pi(): """Compute Pi to the current precision. >>> print pi() - 3.141592653589793238462643383279502887 + 3.141592653589793238462643383 """ - getcontext().prec += 9 # extra digits for intermediate steps + getcontext().prec += 2 # extra digits for intermediate steps three = Decimal(3) # substitute "three=3.0" for regular floats lastc, t, c, n, na, d, da = 0, three, 3, 1, 0, 0, 24 while c != lastc: @@ -943,22 +943,22 @@ def pi(): d, da = d+da, da+32 t = (t * n) / d c += t - getcontext().prec -= 9 - return c + getcontext().prec -= 2 + return c + 0 def exp(x): """Return e raised to the power of x. Result type matches input type. >>> print exp(Decimal(1)) - 2.718281828459045235360287471352662498 + 2.718281828459045235360287471 >>> print exp(Decimal(2)) - 7.389056098930650227230427460575007813 + 7.389056098930650227230427461 >>> print exp(2.0) 7.38905609893 >>> print exp(2+0j) (7.38905609893+0j) """ - getcontext().prec += 9 # extra digits for intermediate steps + getcontext().prec += 2 # extra digits for intermediate steps i, laste, e, fact, num = 0, 0, 1, 1, 1 while e != laste: laste = e @@ -966,20 +966,20 @@ def exp(x): fact *= i num *= x e += num / fact - getcontext().prec -= 9 - return e + getcontext().prec -= 2 + return e + 0 def cos(x): """Return the cosine of x as measured in radians. >>> print cos(Decimal('0.5')) - 0.8775825618903727161162815826038296521 + 0.8775825618903727161162815826 >>> print cos(0.5) 0.87758256189 >>> print cos(0.5+0j) (0.87758256189+0j) """ - getcontext().prec += 9 # extra digits for intermediate steps + getcontext().prec += 2 # extra digits for intermediate steps i, laste, e, fact, num, sign = 0, 0, 1, 1, 1, 1 while e != laste: laste = e @@ -988,20 +988,20 @@ def cos(x): num *= x * x sign *= -1 e += num / fact * sign - getcontext().prec -= 9 - return e + getcontext().prec -= 2 + return e + 0 def sin(x): """Return the cosine of x as measured in radians. >>> print sin(Decimal('0.5')) - 0.4794255386042030002732879352155713880 + 0.4794255386042030002732879352 >>> print sin(0.5) 0.479425538604 >>> print sin(0.5+0j) (0.479425538604+0j) """ - getcontext().prec += 9 # extra digits for intermediate steps + getcontext().prec += 2 # extra digits for intermediate steps i, laste, e, fact, num, sign = 1, 0, x, 1, x, 1 while e != laste: laste = e @@ -1010,7 +1010,7 @@ def sin(x): num *= x * x sign *= -1 e += num / fact * sign - getcontext().prec -= 9 - return e + getcontext().prec -= 2 + return e + 0 \end{verbatim} |