This is one of those highly-application specific things. It may help in some cases and not in others. (In the vast majority of cases, a straight-forward multiplication is still best.) The “intuitive” way of doing this is just to extract the bits into a 64-bit integer and add the shift value directly into the exponent. … Read more
They are being divided in integer arithmetics. So dividing integer a by integer b you get how many times b fits into a. Also a % b will give you a remainder of a division. So (a / b ) * b + a % b = a
You should cast before you divide, but also you were missing a subquery to get the total count from the table. Here’s the sample. select random_int, count(random_int) as Count, cast(count(random_int) as decimal(7,2)) / cast((select count(random_int) from test) as decimal(7,2)) as Percent from test group by random_int order by random_int;
From ISO14882:2011(e) 5.6-4: The binary / operator yields the quotient, and the binary % operator yields the remainder from the division of the first expression by the second. If the second operand of / or % is zero the behavior is undefined. For integral operands the / operator yields the algebraic quotient with any fractional … Read more
You’re dividing integers, which means that you’re using integer division. In integer division the fractional part of the result is thrown away. Try the following: float res = (float) quantity / standard; ^^^^^^^ The above forces the numerator to be treated as a float which in turn promotes the denominator to float as well, and … Read more
If this is not the right answer, what CAN we use for exact division in financial calculation? (I mean, I don’t have a finance major, but they still use division, right???). Then I was in primary school1, they taught me that when you divide by 1 by 3 you get a 0.33333… i.e. a recurring … Read more
The reason the quotients in your test case are not equal is that in the math.floor(a/b) case, the result is calculated with floating point arithmetic (IEEE-754 64-bit), which means there is a maximum precision. The quotient you have there is larger than the 253 limit above which floating point is no longer accurate up to … Read more
To measure is to know (all timings on a Macbook Pro 2.8Ghz i7): >>> import sys, timeit >>> sys.version_info sys.version_info(major=2, minor=7, micro=12, releaselevel=”final”, serial=0) >>> timeit.timeit(‘divmod(n, d)’, ‘n, d = 42, 7’) 0.1473848819732666 >>> timeit.timeit(‘n // d, n % d’, ‘n, d = 42, 7’) 0.10324406623840332 The divmod() function is at a disadvantage here because … Read more
Unless you’re working in a shop and a codebase where bit-shifting is common then, IMHO, you’re risking obfuscation. Yes, the expressions may be logically equivalent but: A n00b might get confused by the alternate syntax An old guy who hasn’t had to do any bit-shifting since college, like myself, might get confused If you bit … Read more