double

问题 I've searched all over the net, but I could not find a solution to my problem. I simply want a function that rounds double values like MS Excel does. Here is my code: #include <iostream> #include "math.h" using namespace std; double Round(double value, int precision) { return floor(((value * pow(10.0, precision)) + 0.5)) / pow(10.0, precision); } int main(int argc, char *argv[]) { /* The way MS Excel does it: 1.27815 1.27840 -> 1.27828 1.27813 1.27840 -> 1.27827 1.27819 1.27843 -> 1.27831 1

问题 I know all the numerical implications, that is, the possible rounding issues inherent to floating point formats, but in my case I have DECIMAL columns in MySQL that I want to convert to DOUBLE straight in the MySQL query rather than down stream. Could anyone help? 回答1: SELECT my_decimal_field + 0E0 FROM my_table 回答2: It seems not possible to cast it to DOUBLE which brings problems if you do calculations and for example want to ROUND() a DECIMAL 12,2 in the third digit. Using ROUND(foo * bar,2

问题 >> C = [{1} {2} ; {'@CF'} {2}] C = [ 1] [2] '@CF' [2] >> whos C Name Size Bytes Class Attributes C 2x2 478 cell How can I convert C into double so that: >> C C = 1 2 NaN 2 I've tried str2double(C) . It returns: NaN NaN NaN NaN 回答1: Find the non numeric values with isnumeric, queried by cellfun. Use that with logical indexing to extract the numeric values: C = [{1} {2} ; {'@CF'} {2}]; isnum = cellfun(@isnumeric,C); result = NaN(size(C)); result(isnum) = [C{isnum}]; 回答2: C = [{1} {2} ; {'@CF'}

问题 >> C = [{1} {2} ; {'@CF'} {2}] C = [ 1] [2] '@CF' [2] >> whos C Name Size Bytes Class Attributes C 2x2 478 cell How can I convert C into double so that: >> C C = 1 2 NaN 2 I've tried str2double(C) . It returns: NaN NaN NaN NaN 回答1: Find the non numeric values with isnumeric, queried by cellfun. Use that with logical indexing to extract the numeric values: C = [{1} {2} ; {'@CF'} {2}]; isnum = cellfun(@isnumeric,C); result = NaN(size(C)); result(isnum) = [C{isnum}]; 回答2: C = [{1} {2} ; {'@CF'}

问题 I have a function getSlope which takes as parameters 4 doubles and returns another double calculated using this given parameters in the following way: double QSweep::getSlope(double a, double b, double c, double d){ double slope; slope=(d-b)/(c-a); return slope; } The problem is that when calling this function with arguments for example: getSlope(2.71156, -1.64161, 2.70413, -1.72219); the returned result is: 10.8557 and this is not a good result for my computations. I have calculated the

问题 void instert(NODE**root, int value) { ... insert(&(*root)->left,value); ... } void search(NODE*root, int value) { ... search(root->left, value); ... } Why we use "&" here: insert(&(*root)->left,value); But we do not use "&" here: search(root->left, value); 回答1: An extra level of indirection is added to insert function so that it could modify the pointer. This is not necessary in case of the search function, because it never modifies the pointer passed to it. Specifically, there needs to be a

问题 void instert(NODE**root, int value) { ... insert(&(*root)->left,value); ... } void search(NODE*root, int value) { ... search(root->left, value); ... } Why we use "&" here: insert(&(*root)->left,value); But we do not use "&" here: search(root->left, value); 回答1: An extra level of indirection is added to insert function so that it could modify the pointer. This is not necessary in case of the search function, because it never modifies the pointer passed to it. Specifically, there needs to be a

问题 Keeps throwing, what is wrong in this part of my code, when I want to return cells I receive this error Cannot implicitly convert type 'System.Collections.Generic.List' to 'double' : public double readFileToList(string Path) { var cells = new List<double>(); string path = label3.Text; if (File.Exists(path)) { double temp = 0; cells.AddRange(File.ReadAllLines(path) .Where(line => double.TryParse(line, out temp)) .Select(l => temp) .ToList()); int totalCount = cells.Count(); cellsNo.Text =

问题 I'm completely new to coding, so please keep this in mind before commenting. So I've been trying to get into coding for a while, and today I went to the library and picked up a book called "programming in c++". I've written some basic programs, but I have gotten stuck at one point, I have no idea how to create a function that makes sure that when the user is prompted for a double, what they enter is valid. (If the user enters a character like 'k', the program just breaks). I searched here and

问题 #define MAX 100 double velocity[MAX]; for (itr = 0; itr < velocity[0]; itr = itr + 1) { velocity[itr] = velocity[0] - (1*itr); distance[itr] = rk4_solve(itr, velocity); cout << setw(5) << itr << setw(9) << velocity[itr] << setprecision(4) << setw(10) << distance[itr] << endl; } I am trying to input values into the array but for some reason I get the error: i Invalid types 'double [100][double]' for array subscript for the 3 lines inside the for loop. 回答1: itr must be an int (or other integer