From Go’s FAQ, The standard library’s purpose is to support the runtime, connect to the operating system, and provide key functionality that many Go programs require, such as formatted I/O and networking. It also contains elements important for web programming, including cryptography and support for standards like HTTP, JSON, and XML. There is no clear … Read more
This is how the C library function abs() does it in assembly without branching: abs(x) = (x XOR y) – y where y = x >> 31 (assuming 32-bit input), and >> is arithmetic right shift operator. Explanation of the above formula: We want to generate 2’s complement of negative x only. y = 0xFFFFFFFF, … Read more
Use pandas.DataFrame.abs(). import pandas as pd df = pd.DataFrame(data={‘count’:[1, -1, 2, -2, 3, -3]}) df[‘count’] = df[‘count’].abs() print(df) count #0 1 #1 1 #2 2 #3 2 #4 3 #5 3
There is a great trick to calculate the absolute value of a 2s-complement integer without using an if statement. The theory goes, if the value is negative you want to toggle the bits and add one, otherwise you want to pass the bits through as is. A XOR 1 happens to toggle A and A … Read more
Assuming 32-bit words, as stated in the question: For negative x, x >> 31 is implementation-defined in the C and C++ standards. The author of the code expects two’s complement integers and an arithmetic right-shift, in which x >> 31 produces all zero bits if the sign bit of x is zero and all one … Read more
The “conditional abs” you propose is not equivalent to std::abs (or fabs) for floating point numbers, see e.g. #include <iostream> #include <cmath> int main () { double d = -0.0; double a = d < 0 ? -d : d; std::cout << d << ‘ ‘ << a << ‘ ‘ << std::abs(d); } output: … Read more
It’s likely because there a built-in functions with the same name, abs. The same is true for np.amax, np.amin and np.round_. The aliases for the NumPy functions abs, min, max and round are only defined in the top-level package. So np.abs and np.absolute are completely identical. It doesn’t matter which one you use. There are … Read more
Integer.MIN_VALUE is -2147483648, but the highest value a 32 bit integer can contain is +2147483647. Attempting to represent +2147483648 in a 32 bit int will effectively “roll over” to -2147483648. This is because, when using signed integers, the two’s complement binary representations of +2147483648 and -2147483648 are identical. This is not a problem, however, as … Read more
>>> n = -42 >>> -n # if you know n is negative 42 >>> abs(n) # for any n 42 Don’t forget to check the docs.