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Designing function f(f(n)) == -n
...oof of why such a function can't exist, for all numbers, if it doesn't use extra information(except 32bits of int):
We must have f(0) = 0. (Proof: Suppose f(0) = x. Then f(x) = f(f(0)) = -0 = 0. Now, -x = f(f(x)) = f(0) = x, which means that x = 0.)
Further, for any x and y, suppose f(x) = y. We w...
Convert PDF to clean SVG? [closed]
...k_dir=%CD%"
:: setup counter
set "count=1"
:: setup file search and save string
set "_work_x1=pdf"
set "_work_x2=svg"
set "_work_file_str=*.%_work_x1%"
:: setup inkscape commands
set "_inkscape_path=D:\InkscapePortable\App\Inkscape\"
set "_inkscape_cmd=%_inkscape_path%inkscape.exe"
:: ===== FIND...
How to split a string and assign it to variables
In Python it is possible to split a string and assign it to variables:
9 Answers
9
...
Is 1.0 a valid output from std::generate_canonical?
...curs quite often in real-world calculations) when x is close to zero. The "extra precision" near multiples of π is generally just a side effect of that.
– Ilmari Karonen
Sep 4 '14 at 20:16
...
Using Excel OleDb to get sheet names IN SHEET ORDER
...param name="excelFile">The excel file.</param>
/// <returns>String[]</returns>
private String[] GetExcelSheetNames(string excelFile)
{
OleDbConnection objConn = null;
System.Data.DataTable dt = null;
try
{
// Connection String. Change the excel file to t...
How to read and write INI file with Python3?
...omplete read, update and write example.
Input file, test.ini
[section_a]
string_val = hello
bool_val = false
int_val = 11
pi_val = 3.14
Working code.
try:
from configparser import ConfigParser
except ImportError:
from ConfigParser import ConfigParser # ver. < 3.0
# instantiate
conf...
How to use the IEqualityComparer
...class.
public class Person : IEquatable<Person>
{
public Person(string name, string hometown)
{
this.Name = name;
this.Hometown = hometown;
}
public string Name { get; set; }
public string Hometown { get; set; }
// can't get much simpler than this!
...
How do I use pagination with Django class based generic ListViews?
... I have been doing this, but the problem I find, is when I do extra processing on objects in the queryset, it applys them to all of the results in the database. So for a query that returns 100 objects, but shows only ten objects per page, the extra processing will be done on 100 objects...
Align two inline-blocks left and right on same line
...:after part and justified the content.
In order to solve the issue of the extra space that is inserted with the after pseudo-element one can do a trick of setting the font-size to 0 for the parent element and resetting it back to say 14px for the child elements. The working example of this trick ca...
Parameterize an SQL IN clause
...ls|scruffy|rubyonrails|'
LIKE '%|' + Name + '|%'
So here's the C# code:
string[] tags = new string[] { "ruby", "rails", "scruffy", "rubyonrails" };
const string cmdText = "select * from tags where '|' + @tags + '|' like '%|' + Name + '|%'";
using (SqlCommand cmd = new SqlCommand(cmdText)) {
c...