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What does “coalgebra” mean in the context of programming?
...noids and so on. Most of the time, these things are introduced in terms of sets, but since we're among friends, I'll talk about Haskell types instead. (I can't resist using some Greek letters though—they make everything look cooler!)
An algebra, then, is just a type τ with some functions and ide...
What is the most efficient way of finding all the factors of a number in Python?
...
from functools import reduce
def factors(n):
return set(reduce(list.__add__,
([i, n//i] for i in range(1, int(n**0.5) + 1) if n % i == 0)))
This will return all of the factors, very quickly, of a number n.
Why square root as the upper limit?
sqrt(x) * sqrt...
How can I use an array of function pointers?
...object_class->constructor = gtk_button_constructor;
gobject_class->set_property = gtk_button_set_property;
gobject_class->get_property = gtk_button_get_property;
And in gtkobject.h you find the following declarations:
struct _GtkObjectClass
{
GInitiallyUnownedClass parent_class;...
Efficient evaluation of a function at every cell of a NumPy array
...ds to do one less multiplication and addition (for calculating the data offset) at each iteration. Plus it works for arbitrarily dimensioned arrays. Might be slower on very small arrays, tho.
– blubberdiblub
Oct 9 '11 at 8:13
...
List comprehension: Returning two (or more) items for each item
...='list(chain.from_iterable((f(x), g(x)) for x in range(3)))',
setup='gc.enable(); from itertools import chain; f = lambda x: x + 2; g = lambda x: x ** 2')
print timeit(stmt='list(chain.from_iterable(fg(x) for x in range(3)))',
setup='gc.enable(); from itertools import chai...
Get most recent file in a directory on Linux
... I like *(.om[1]), but I usually want to find the newest file in a set of folders, ie. /path/to/folders*/*(.om[1]), which unfortunately only returns the newest file in all matched folders. See unix.stackexchange.com/questions/552103/… on how to accomplish it over multiple folders.
...
Why can a function modify some arguments as perceived by the caller, but not others?
...
It´s because a list is a mutable object. You´re not setting x to the value of [0,1,2,3], you´re defining a label to the object [0,1,2,3].
You should declare your function f() like this:
def f(n, x=None):
if x is None:
x = []
...
...
Find XOR of all numbers in a given range
...
I have solved the problem with recursion. I simply divide the dataset into an almost equal part for every iteration.
public int recursion(int M, int N) {
if (N - M == 1) {
return M ^ N;
} else {
int pivot = this.calculatePivot(M, N);
if (pivot + 1 == N) {
...
LINGO使用指南 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...LINGO软件，编制程序如下：
model:
!6发点8收点运输问题;
sets:
warehouses/wh1..wh6/: capacity;
vendors/v1..v8/: demand;
links(warehouses,vendors): cost, volume;
endsets
!目标函数;
min=@sum(links: cost*volume);
!需求约束;
@for(vendors(J):
@sum(warehous...
Printf width specifier to maintain precision of floating-point value
...uses.
C has 2 families of macros in <float.h> to help us.
The first set is the number of significant digits to print in a string in decimal so when scanning the string back,
we get the original floating point. There are shown with the C spec's minimum value and a sample C11 compiler.
FLT_DE...