C++ :: First Derivative With Many Variables?
Jun 19, 2013
I have First derivative function implemented in C++. More details [URL] ...
In programming, I'm dealing with a lot of variables. x, y, z & x', y', z' & x'', y'', z'' These are only for one device. The problem is how can I deal with velocities and accelerations the way I did with positions? This is the code
while (1) {
/* Perform a synchronous call to copy the most current device state.
This synchronous scheduler call ensures that the device state is obtained in a thread-safe manner. */
hdScheduleSynchronous(copyDeviceDataCallback, ¤tData, HD_MIN_SCHEDULER_PRIORITY);
x_Position[2] = currentData.m_devicePosition[0];
x_Position[3] = currentData.m_devicePosition[0];
x_Position[4] = currentData.m_devicePosition[0];
[Code] ....
I've tried to create x_Velocity[5] and
x_Position[2] = currentData.m_devicePosition[0];
x_Position[3] = currentData.m_devicePosition[0];
x_Position[4] = currentData.m_devicePosition[0];
[Code] ....
I'm trying also to store x_Velocity in vector. Every time I deal with whether array or vector, the first two points of x position are affected because I'm calling the function for the velocity.
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Nov 12, 2014
How to get the derivative of a polynomial.
Code:
#include "p.h"#include <stdio.h>
#include <stdlib.h>
/*----------------------------------------------*/
/* Sets all coefficients to 0 */
/*--------------------------------------------- */
void initialize(Polynomial p)
[Code] .....
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Feb 27, 2014
So I'm trying to make a derivative calculator that can do simple polynomial calculations in a very specific way. If you read the cout line you'll understand rather quickly.
#include<iostream>
#include<cstdlib>
#include<string>
#include<cstring>
using namespace std;
struct variable {
char Variable,degree,constant;
[Code] ....
I get an error at line 33 and 37 saying error: request for member '_cstr' in 'constant', which is of non-class type 'char'
and the same line with 'degree' instead of constant.
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Feb 23, 2014
I'm very new to C++ so I've been trying to run through some code examples to begin to learn basic structures and syntax, but I've recently run into a problem using examples from the 7th ed. of Sams Teach Yourself C++. I'm using the code provided within one of the examples that allows you to specify and multiply two variables, but when I compile and run the executable the final output seems to only show the first variable and b/c of this the multiplication operation does not work.
Here is a my example code:
Code:
#include <iostream>
using namespace std;
int main() {
cout << "This program will multiply two numbers" << endl;
[Code] ....
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Nov 19, 2013
So here is what i need i need a way i can add 3 variables one after the other example:
int a = 1;
int b = 2;
int c = 3;
//Here comes my problem
int d = a + b + c;
When I write it like thet d = 6 ,
but I need it to be 123,
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Mar 19, 2013
I am just a beginner in c++..I am making a program on a physics formula PV=nRT(this is formula of ideal gas equation)i have build the program and it run excellently but i want to improve this i am using a condition p==0 because i want to find 'p' but the problem is every time i run the program i have to input p=0 in the screen but i want the program to skip "p" ( take automatically "p" as 0 when i press enter and got to another varibles)
#include <iostream>
#include <cmath>
using namespace std;
int main()
[code].....
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Jul 8, 2014
How are map variables initialized?
PLEASE EXPLAIN THE FOLLOWING CODE TO ME?
// accessing mapped values
#include <iostream>
#include <map>
#include <string>
int main () {
std::map<std::string, int> mymap;
[Code]...
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Feb 6, 2013
Suppose x, y, and z are int variables. What value is assigned to each of these variables after the last statement executes?
x = 4; y = 11;
z = y - 2 * x;
x = z + y;
y = x + 5 * z;
w = x - y + 2 * z;
x = y + w - x;
-w;
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May 26, 2014
So I am trying to develop a sort of 2d spacesim engine for creating games in C++. The project uses SFML for graphics, and I am currently trying to compile it on Linux using g++.
The main issue that I am wrestling with is that of simulation objects having their position, velocity, and rotation variables constantly getting set to NaN for reasons that are beyond me. The behaviour is not consistent, and occasionally will occur or not occur without any discernible pattern.
The github repo for the code is here: [URL] ....
I understand that NaN values can spread easily by operations on one another, but I cant seem to figure out where the initial issue is occurring here.
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Mar 6, 2015
I'm trying to use two variables for two different functions.
#include "stdafx.h"
#include <iostream>
#include <cstdlib>
[Code].....
Every time screen2() runs it always outputs "Numbers entered were 0 and 0". I want the numbers that were entered in by the user in screen1() to be displayed.
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Feb 23, 2014
im creating an address book. One address book contains a ListBox, New User button, Edit User and Remove User button. The first form is suppose to allow you to view the users you've created on the ListBox and you can decide whether you want to remove it, create a new one or simply edit the user. Now The second form simply contains labels and textbox along with a save button. I'm having a bit of issue figuring out the ListBox. I want to be able to create a user and have the user be posted on the ListBox. I read that i must instantiate listbox then simply add it. Now on my form2 i have a for loop that loops through an Array of String were all the users will be created on. How can i call that array of string on to the form1?
Form 1:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
[code].....
EDIT:I just figured out that to call a variable from one form to another you simply instantiate the form then simply call it. PS. must be set to public:
ListBox1 createUser = new ListBox1();
createUser.userString[0];
why doesnt it show the windows when i run without debugging?
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Mar 9, 2014
For a few days now I have been trying to call variables (globes) from another CPP file so I can add/subtract data from them and use them in other places. I have my defines.h file working which contains all my constants but my defines.cpp (which is required to hold all the non constants) are not. Anyways I am getting the error :
Error1error LNK2001: unresolved external symbol "float MONEY" (?MONEY@@3MA)C:UsersJacksdocumentsvisual studio 2012ProjectsAssignmnet2Assignmnet2main.objAssignmnet2
My defines.cpp
//#include "Defines.h"
using namespace std;
//Game mechanic variables
extern float STOCK_LEMONS;
extern float STOCK_SUGAR;
extern float STOCK_ICE;
[Code] .....
If I were to un-comment the "float money = 50" it would work...
I also didn't include my defines.cpp into my defines.h as I got to many errors...
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Jun 24, 2014
This is my first time working with C++ and I have put together this program and came up with two errors and I am unsure what it is wanting me to do. The errors I got are:
1>c:usersownerdocumentsvisual studio 2010projectsweek5week5passing_by_value.cpp(30): error C2064: term does not evaluate to a function taking 1 arguments
1>c:usersownerdocumentsvisual studio 2010projectsweek5week5passing_by_value.cpp(38): error C2064: term does not evaluate to a function taking 1 arguments
#include<iostream>
using std::cin;
using std::cout;
using std::endl;
[Code].....
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Sep 26, 2014
I don't have in depth code or anything. I tried this but can't seem to wrap my head around it.
Code: //header.h
namespace test {
int arr[5];
[Code] ....
Also tried putting int arr[5] in a Test class within test.h.
I have 2 structs in another file, the main, and want to make an instance of the arr variable, in a separate header, for each.
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Aug 7, 2013
I have a structure
Code: struct time{
char hours;
char minutes;
char seconds;
char dummy;
};
I have kept dummy as the data to be aligned.I will update hours, minutes, and seconds , but will not use dummy in any case.
If I don't initialize 'dummy' does it make any errors ?
Do I need to initialize hours, minutes, seconds as well before I use the structure ?
If so is there any particular reason ?
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Sep 26, 2014
I am working on a homework assignment and have most of the program working, but when I try to compile it keeps telling me to initialize the coin variables in each class. However, they are supposed to be added then removed so I don't want to set them back to zero.
Rewrite the Purse program given in Page 35 with functions to perform insert and remove operations. The function insert (int p, int n, int d, int q) will initialize pennies, nickels, dimes and quarters. The function dollars() will return the dollars. The function remove (int p, int n, int d, int q) will subtract pennies, nickels, dimes and quarters. The function display() returns a new String to print the content of the purse with remaining pennies, nickels, dimes and quarters.
Code:
usingnamespace std;
int insert_money (int *p, int *n, int *d, int *q);
int remove_money (int *p, int *n, int *d, int *q);
int dollars();
int main()
[Code] ....
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Dec 14, 2013
The situation is the following :
Code:
vector<int>& function(int a , int b){
vector<int> s(3000000);
vector<int> xxx(4);
return xxx
}
Not to board people with details but if i am returning the the reference to a vector xxx what happens to vector s. is it destroyed ?? it should be, but i don't see it on my memory map (memory is not released) . can this be or should i go and search for error on some other place.....
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Mar 4, 2014
What the code below is not doing is returning a value for item to my variables (item1, item2, etc..) I'm not sure how I can make a function prototype that will ask for input and basically recycle after going through the program to a new value for each item. I also need to input individual tax for each item. I will also post it in this message:
double tax, item,salesTax;
double cost(double);
double CalcSalesTax(double);
main(){
double total,item1, item2, item3, item4, item5, tax1, tax2, tax3,tax4,tax5;
[Code].....
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May 22, 2013
working on this code I have encountered a few issues. My program lists the occurrence of each letter but i'm unsure of how to enable numeric variables. how to improve the overall quality of the code.
Code:
#include <stdio.h>
#include <string.h>
int main()
{
char string[100], ch;
int c = 0, count[26] = {0};
printf("Enter a string
[Code]...
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Oct 15, 2014
I have made an application and I have basically solved everything. But the only problem is that I am using global variables because it felt like the smoothest, so my program is built on it.
But now I've read around and I understand that you should not use these(?). Do you think pointers is the best think to use instead?I have previously declared my board array and some variables as global and I want them in alot of functions.I have read and understand the procedure for the use of pointers so I can use my int's in the other functions by doing like this? Code: #include <stdio.h>
int justprint();
int main()
{
int Row = 2;
int Column = 2;
int *pRow = &Row;
int *pColumn = &Column;
[code]...
But how do I do it with an array like this one? If I declare it in the main function, and then want to use it in other functions.Or are there better, easier solutions?
Code: char game[3][3]={{0,0}};
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Mar 6, 2015
I have this code where I am trying to retrieve the contents of the variable dev1 and dev2. for some reason when i compile and run I am getting 0 and 0.
Code:
typedef struct {
uint32_t x;
uint32_t y;
} sample;
void get_sample(sample *one)
[Code].....
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Feb 26, 2013
I am new to C programming and I am just wondering how to multiply / divide two different variables which the user type in as the promt is asking like this:
Code:
void inmatning3 (double *a, double *b) {
printf("Mata in tv217 stycken flyttal: "); /* asks you to type in 2 numbers */
scanf("%lf %lf", a, b);
}
When you've enterd the two numbers I need to eather multiply or divide the two variables "a" & "b" .....
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Apr 5, 2013
why does the 2 variables, loanAmt and intRatem not work when they are multiplied together. The question is " Write a program that calculates the remaining balance on a loan after the first, second and third monthly payments. "
Code:
#include <stdio.h>
void a5()
{
float loanAmt, intRate, intRatem, dintRate, payment, pay1, pay2, pay3,test;
printf("Enter amount of loan:");
scanf("%f", &loanAmt);
}
[code].....
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Jun 29, 2014
I'm playing around with GTK+ 2.x and currently I have a button to call a function like so:
Code:
void selectmod(GtkWidget *downloadbutton, GtkComboBox *modlist, gchar *data){
gchar *mod = gtk_combo_box_get_active_text(modlist);
printf("
%s", mod);
}
How can I pass the *mod variable to another function?
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Mar 1, 2013
If I have a static variable in a class e.g. a pointer to another class like this: (B is another class)
class A {
public:
static B* cB;
};
Then I set that variable and create multiple instances of class A like this:
A::cB = new B;
As = new A[Number];
Then will the value of cB be the same across all instances?
I cannot pass the class pointer in the constructor as I need to create an array of instances. I tried this method but I get linker error.... unresolved external.
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Aug 3, 2013
I've been attempting to create a game with curses and I keep running into the problem of scope. I want to change or use variables of a different class in a different header file. But I don't know if I should use pointers, references or neither. Should I be programming in a manner that doesn't make it necessary to use variables outside of their class?
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