I have been searching on Google an in this forum for a while, but I could not find any answer or tip for my problem. Tutorials couldn't help me either...
I want to redistribute some points, stored in a vector p_org. (x-value is stored as double).
Therefore I have the function distribute, which is defined in maths.h
distribute_tanh(&p_org_temp,&p_new_temp,iz,spacing[0],spacing[1],l_rot[(kk+1)*iz-2],status);
The function distribute_tanh does look like this:
inline void distribute_tanh (std::vector<double> *p_org, std::vector<double> *p_new, const int n_points, double spacing_begin, double spacing_end, const double total_length, double status){
//if status == 0: FLAP, if status == 1: SLAT
std::cout << "spacing_begin: " << spacing_begin << " spacing_end: " << spacing_end << std::endl;
double s_begin = spacing_begin / total_length;
double s_end = spacing_end / total_length;
double A = sqrt(s_end/s_begin);
double B = 1 / (sqrt(s_end*s_begin)*n_points);
std::cout << "A: " << A << " B: " << B << std::endl;
std::vector<double> u (n_points);
std::vector<double> sn (n_points);
double dx;
double dy;
std::cout << "Control at the beginning: p_org: " << (p_org) << " p_new: " << (p_new) << " n_points: " << n_points << " s_begin: " << s_begin << " s_end: " << s_end << " total_length: " << total_length << std::endl;
//problem no. 1
for (int i=0;i<n_points;i++){
if (B > 1.001) {
if (B < 2.7829681) {
double Bq=B-1;
dy=sqrt(6*Bq)*(1-0.15*Bq+0.057321429*pow(Bq,2)-0.024907295*pow(Bq,3)+0.0077424461*pow(Bq,4)-0.0010794123*pow(Bq,5));
} else if (B > 2.7829681) {
double Bv=log(B);
double Bw=1/B-0.028527431;
dy=Bv+(1+1/Bv)*log(2*Bv)-0.02041793+0.24902722*Bw+1.9496443*pow(Bw,2)-2.6294547*pow(Bw,3)+8.56795911*pow(Bw,4);
}
u[i]=0.5+(tanh(dy*(i*(1.0/n_points)-0.5))/(2*tanh(dy/2)));
}
else if (B < 0.999) {
if (B < 0.26938972) {
dx=M_PI*(1-B+pow(B,2)-(1+(pow(M_PI,2))/6)*pow(B,3)+6.794732*pow(B,4)-13.205501*pow(B,5)+11.726095*pow(B,6));
} else if (B > 0.26938972) {
double Bq=1-B;
dx=sqrt(6*Bq)*(1+0.15*Bq+0.057321429*pow(Bq,2)+0.048774238*pow(Bq,3)-0.053337753*pow(Bq,4)+0.075845134*pow(Bq,5));
}
u[i]=0.5+(tan(dx*(i*(1.0/n_points)-0.5))/(2*tan(dx/2)));
}
else {
u[i]=i*(1.0/n_points)*(1+2*(B-1)*(i*(1.0/n_points)-0.5)*(1-i*(1.0/n_points)));
}
sn[i]=u[i]/(A+(1.0-A)*u[i]);
std::cout << "sn(i): " << sn[i] << std::endl;
std::cout << "p_org[n_points]: " << &p_org[n_points-1] << std::endl;
if(status==0){
//p_new[i]=p_org[0]+(total_length*sn[i]);
std::cout << "FLAP maths.h" << std::endl;
}
//Here is the problem no. 2
else if(status==1){
//p_new[i]=p_org[0]-(total_length*sn[i]);
std::cout << "SLAT maths.h" << std::endl;
}
//std::cout << "p_new in math: " << p_new << std::endl;
}
}
My problem is, that I am unable to access the value of p_org or p_new. At the beginning I would like to give out the value of p_org and p_new. If I try it with a *, the compiler is complaining: error: no operator "<<" matches these operands
operand types are: std::basic_ostream> << std::vector>
std::cout << "Control at the beginning: p_org: " << (*p_org) << " p_new: " << (*p_new) << " n_points: " << n_points << " s_begin: " << s_begin << " s_end: " << s_end << " total_length: " << total_length << std::endl;
If I leave the * off, I get the addresses of p_org and p_new.
At the end of the code I would like to write the new value to p_new. If I use * to access the value, the compiler is complaining, if I leave it off, its complaining too with the following message:
error: no operator "-" matches these operands
operand types are: std::vector<double, std::allocator<double>> - double
p_new[i]=p_org[0]-(total_length*sn[i]);
^
I tried to understand both problems, but until now I had no success.
Thanks for your advice.
Your issue with the compiler error can be cut down to a very simple program.
#include <vector>
void foo(std::vector<int>* pV)
{
pV[0] = 10; // error.
}
int main()
{
std::vector<int> v(10);
foo(&v);
}
The issue is that operator[] as done above works for objects and references, not pointers. Since pv is a pointer, you must dereference it first to obtain the object, and then apply [] to the dereferenced pointer.
void foo(std::vector<int>* pV)
{
(*pV)[0] = 10; // No error
}
The other form of calling operator[] can be also used, but is a bit more verbose:
void foo(std::vector<int>* pV)
{
pv->operator[](0) = 10; // No error
}
However, to alleviate having to do this, pass the vector by reference. Then the "normal" way of using operator[] can be used.
#include <vector>
void foo(std::vector<int>& pV)
{
pV[0] = 10; // No error.
}
int main()
{
std::vector<int> v(10);
foo(v);
}
Related
I am trying to calculate the lpNorm of a vector with the Eigen library.
As it can be seen in the example below, with explicit values, such as v.lpNorm<1>(), it works. But it doesn't work inside the loop, with lpNorm<p>()
How can I fix this?
#include <iostream>
#include <Eigen/Dense>
using Eigen::VectorXd;
int main()
{
int sizev = 3;
int p;
Eigen::VectorXd v(sizev);
v(0) = 3.;
v(1) = 2.;
v(2) = 1.;
// test 1, passes
std::cout << "||v||_" << 1 << " = " << v.lpNorm<1>() << std::endl;
std::cout << "||v||_" << 2 << " = " << v.lpNorm<2>() << std::endl;
std::cout << "||v||_" << 3 << " = " << v.lpNorm<3>() << std::endl;
std::cout << "||v||_" << 4 << " = " << v.lpNorm<4>() << std::endl;
std::cout << "||v||_inf = " << v.lpNorm<Eigen::Infinity>() << std::endl;
// test 2, fails
for (int p=1; p<5; p++)
{
std::cout << "||v||_" << p << " = " << v.lpNorm<p>() << std::endl;
}
return 0;
}
On compilation, I am getting the error
error: no matching member function for call to 'lpNorm'
std::cout << "||v||_" << p << " = " << v.lpNorm<p>() << std::endl;
~~^~~~~~~~~
note: candidate template ignored: invalid explicitly-specified argument for template parameter 'p'
template<int p> EIGEN_DEVICE_FUNC RealScalar lpNorm() const;
^
1 error generated.
You cannot use variable integer as a template argument, it needs to be a compile time constant, such as
constexpr int p = 3;
v.lpNorm<p>();
However, you can still have a kind of compile-time loop using e.g. std::integer_sequence. I modified a bit the example from documentation to call a function:
template<typename T, T... ints>
void exec_constexpr_loop(std::integer_sequence<T, ints...> int_seq, Eigen::Ref<Eigen::VectorXd> v)
{
((v.lpNorm<ints>()), ...);
}
exec_constexpr_loop(std::integer_sequence<int, 1, 2, 3>{}, v);
Live demo with dummy function, works since C++17.
I have a class that I use with the Armadillo package to create a specific kind of matrix. I'm having trouble debugging it, so I would like to use a function I have written called Matlab_Print. It lives in its own .h and .cpp file and is used throughout my code. The class and the function both work perfectly, but I do not seem to be able to combine them.
I have tried #include "Matlab_Print" in SU3.h both before and after the class definition. I really don't want to make the function a class function as I use Matlab_Print frequently. I do have a workaround but it is inconvenient, and at any rate I am looking at this as a learning opportunity.
I trap error messages with a try when calling the SU3 constructor and I get the following:
error: Mat::init(): size is fixed and hence cannot be changed
main.cpp
#include "pch.h"
#include <new>
#include <exception>
#include "SU3.h"
int main(int argc, char *argv[])
{
int icount { 0 };
SU3 *su3[10];
try
{
for (icount = 0; icount < 10; icount++)
{
su3[icount] = new SU3(0.1);
}
}
catch (int param) { cout << "Function " << __func__ << " int " << param << " exception in memory allocation for su3" << std::endl; exit(1); }
catch (char param) { cout << "Function " << __func__ << " char " << param << " exception in memory allocation for su3" << std::endl; exit(1); }
catch (...) { cout << "Function " << __func__ << " exception in memory allocation for su3" << std::endl; exit(1); }
return 0;
}
SU3.h
#include "pch.h"
#include "SU3.h"
#include <armadillo>
#include "Matlab_Print.h"
class SU3
{
public:
arma::Mat<cx_double>::fixed<3, 3> *X;
SU3(const double epsilon);
};
SU3.cpp
SU3::SU3(const double epsilon) // simplifed so that epsilon plays no role
{
const std::complex<double> o{ 1.0 , 0.0 }; // complex 1
const std::complex<double> z{ 0.0 , 1.0 }; // complex 0
X = new arma::Mat<cx_double>::fixed<3, 3>{ fill::zeros }; //// solution to problem: define and initialize pointer ////
*X = { { o, z, z},
{ z, o, z},
{ z, z, o} };
Matlab_Print(*X, "SU3"); // this is the line I wish to use
}
Matlab_Print.h
#include <armadillo>
#include <complex>
void Matlab_Print(arma::Mat<cx_double>::fixed<3, 3> Matrix, std::string T);
Matlab_Print.cpp
#include "pch.h"
#include "Matlab_Print.h"
void Matlab_Print(arma::Mat<cx_double>::fixed<3, 3> Matrix, std::string T)
{
std::cout << std::endl;
std::cout << "RE = [" << std::real(Matrix(0, 0)) << " " << std::real(Matrix(0, 1)) << " " << std::real(Matrix(0, 2)) << "; ";
std::cout << std::real(Matrix(1, 0)) << " " << std::real(Matrix(1, 1)) << " " << std::real(Matrix(1, 2)) << "; ";
std::cout << std::real(Matrix(2, 0)) << " " << std::real(Matrix(2, 1)) << " " << std::real(Matrix(2, 2)) << "]; " << std::endl;
std::cout << "IM = [" << std::imag(Matrix(0, 0)) << " " << std::imag(Matrix(0, 1)) << " " << std::imag(Matrix(0, 2)) << "; ";
std::cout << std::imag(Matrix(1, 0)) << " " << std::imag(Matrix(1, 1)) << " " << std::imag(Matrix(1, 2)) << "; ";
std::cout << std::imag(Matrix(2, 0)) << " " << std::imag(Matrix(2, 1)) << " " << std::imag(Matrix(2, 2)) << "]; " << std::endl;
std::cout << T << " = RE + 1i*IM;" << std::endl;
}
Thank you for your patience. I hope this is all of the information you need.
As #uneven_mark notes, you have undefined behavior in SU3::SU3, because you are dereferencing X without initializing it first. You probably don't want a pointer here.
N.b. you don't need new to create objects of class type.
class SU3
{
public:
arma::Mat<cx_double>::fixed<3, 3> X;
SU3(const double epsilon);
};
using namespace std::literals::complex_literals;
SU3::SU3(const double epsilon)
: X({ { 1, 1i, 1i },
{ 1i, 1, 1i },
{ 1i, 1i, 1 } }) // prefer member initialisers over assingments
{
Matlab_Print(X, "SU3");
}
if x > INT_MAX or if x > INT_MIN the function will return 0... or that's what i'm trying to do :)
in my test case i pass in a value that is INT_MAX + 1... 2147483648 ... to introduce integer overflow to see how the program handles it.
i step through... my IDE debugger says that the value immediately goes to -2147483648 upon overflow and for some reason the program executes beyond both of these statements:
if (x > INT_MAX)
if (x < INT_MIN)
and keeps crashes at int revInt = std::stoi(strNum);
saying out of range
Must be something simple, but it's got me stumped. Why isn't the program returning before it ever gets to that std::stoi() given x > INT_MAX? Any help appreciated. Thanks! Full listing of function and test bed below: (sorry having trouble with the code insertion formatting..)
#include <iostream>
#include <algorithm>
#include <string> //using namespace std;
class Solution {
public: int reverse(int x)
{
// check special cases for int and set flags:
// is x > max int, need to return 0 now
if(x > INT_MAX)
return 0;
// is x < min int, need to return 0 now
if(x < INT_MIN)
return 0;
// is x < 0, need negative sign handled at end
// does x end with 0, need to not start new int with 0 if it's ploy numeric and the functions used handle that for us
// do conversion, reversal, output:
// convert int to string
std::string strNum = std::to_string(x);
// reverse string
std::reverse(strNum.begin(), strNum.end());
// convert reversed string to int
int revInt = std::stoi(strNum);
// multiply by -1 if x was negative
if (x < 0)
revInt = revInt * -1;
// output reversed integer
return revInt;
}
};
Main:
#include <iostream>
int main(int argc, const char * argv[]) {
// test cases
// instance Solution and call it's method
Solution sol;
int answer = sol.reverse(0); // 0
std::cout << "in " << 0 << ", out " << answer << "\n";
answer = sol.reverse(-1); // -1
std::cout << "in " << -1 << ", out " << answer << "\n";
answer = sol.reverse(10); // 1
std::cout << "in " << 10 << ", out " << answer << "\n";
answer = sol.reverse(12); // 21
std::cout << "in " << 12 << ", out " << answer << "\n";
answer = sol.reverse(100); // 1
std::cout << "in " << 100 << ", out " << answer << "\n";
answer = sol.reverse(123); // 321
std::cout << "in " << 123 << ", out " << answer << "\n";
answer = sol.reverse(-123); // -321
std::cout << "in " << -123 << ", out " << answer << "\n";
answer = sol.reverse(1024); // 4201
std::cout << "in " << 1024 << ", out " << answer << "\n";
answer = sol.reverse(-1024); // -4201
std::cout << "in " << -1024 << ", out " << answer << "\n";
answer = sol.reverse(2147483648); // 0
std::cout << "in " << 2147483648 << ", out " << answer << "\n";
answer = sol.reverse(-2147483648); // 0
std::cout << "in " << -2147483648 << ", out " << answer << "\n";
return 0;
}
Any test like (x > INT_MAX) with x being of type int will never evaluate to true, since the value of x cannot exceed INT_MAX.
Anyway, even if 2147483647 would be a valid range, its reverse 7463847412 is not.
So I think its better to let stoi "try" to convert the values and "catch" any out_of_range-exception`. The following code illustrates this approach:
int convert() {
const char* num = "12345678890123424542";
try {
int x = std::stoi(num);
return x;
} catch (std::out_of_range &e) {
cout << "invalid." << endl;
return 0;
}
}
I am trying to load freetype chars, stuff them into a texture as subimages and then render them instanced.
While most of it seems to work, right now I have a problem with storing the texture coordinates into a glm::mat2x4 matrix.
As can be seen below each character has a struct with information I right now deem necessary, including a matrix called face, which should store the texture coordinates.
But when it comes to assigning the coordinates, after leaving the loop in which it takes place, suddenly all the values go crazy, without any (wanted/ intended) operation taking place from my side.
After creating the texture atlas with freetype and putting all my structs into the map, I assign the width and height of my texture aw & ah to a storage class called c_atlas.
I calculate the texture coordinates in the loop shown below, make the glm::mat2x4 a 0.0f matrix and then stuff them into it. Couting them into the console gives the values I want.
After leaving the for loop I start another one, browsing over the matrix and cout them into the console, which gives me more or less random values in the range of e^-23 to e^32.
All of this happens in namespace foo and is called in a constructor of a class in the same namespace (sth. like this:)
foo::class::constructor()
{
call_function();
}
int main()
{
foo::class c;
c.call_function();
}
I crafted a minimum working example, but unfortunatly I am not able to replicate the error.
So I have the following loop running (a part of call_function():
namespace foo
{
namespace alphabet
{
const char path_arial[] = "res/font/consola.ttf";
class character
{
public:
glm::vec2 advance;
glm::vec2 bearing;
glm::vec2 size;
glm::vec2 offset;
glm::mat2x4 face;
};
std::map<char, character> char_map;
FT_Library m_ftlib;
FT_Face m_ftface;
GLuint m_VBO, m_VAO;
}
c_atlas ascii;
}
void foo::call_function()
{
//creating all the charactur structs with freetype and store them in the char_map
std::ofstream f("atlas_data.csv", std::ios::openmode::_S_app);
f << "letter;topleft.x;topleft.y;topright.x;topright.y;bottomright.x;bottomright.y;bottomleft.x;bottomleft.y" << std::endl;
for(auto c : alphabet::char_map)
{
std::cout << "b4: " << c.second.offset.x;
c.second.offset /= glm::vec2(aw,ah);
std::cout << "\nafter: " << c.second.offset.x << std::endl;
glm::vec2 ts = c.second.size/glm::vec2(aw,ah);
//couts the right values
uint16_t n = 0;
c.second.face = glm::mat2x4(0.0f);
for(uint16_t i = 0; i < 4; ++i)
{
std::cout << c.first << " at init:\n";
std::cout << c.second.face[0][i] << "\n";
std::cout << c.second.face[1][i] << std::endl;
}
//couts the right values
c.second.face[0][n++] = c.second.offset.x;
c.second.face[0][n++] = c.second.offset.y;
c.second.face[0][n++] = c.second.offset.x+ts.x;
c.second.face[0][n++] = c.second.offset.y;
n = 0;
c.second.face[1][n++]= c.second.offset.x+ts.x;
c.second.face[1][n++] = c.second.offset.y+ts.y;
c.second.face[1][n++] = c.second.offset.x;
c.second.face[1][n++]= c.second.offset.y+ts.y;
for(uint16_t i = 0; i < 4; ++i)
{
std::cout << c.first << " assigned:\n";
std::cout << c.second.face[0][i] << "\n";
std::cout << c.second.face[1][i] << std::endl;
}
//still couts the right values
f << (char)c.first << ";" << c.second.face[0].x << ";" << c.second.face[0].y << ";" << c.second.face[0].z << ";" << c.second.face[0].w << ";" << c.second.face[1].x << ";" << c.second.face[1].y << ";" << c.second.face[1].z << ";" << c.second.face[1].w << std::endl;
//the file also have the right values
}
f.close();
glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
//yet here all the values totally off track, i.e. e^32 or e^-23 (while they should all be between 0.01f - 1.0f)
for(auto i : alphabet::char_map)
{
std::cout << "\ntopleft:\n";
std::cout << "X: " << i.second.face[0].x << " | " << "Y: " << i.second.face[0].x;
std::cout << "\ntopright:\n";
std::cout << "X: " << i.second.face[0].z << " | " << "Y: " << i.second.face[0].w;
std::cout << "\nbotleft:\n";
std::cout << "X: " << i.second.face[1].x << " | " << "Y: " << i.second.face[1].x;
std::cout << "\nbotright:\n";
std::cout << "X: " << i.second.face[1].z << " | " << "Y: " << i.second.face[1].w;
}
}
my mwe:
#include <iostream>
#include <string>
#include "glm/glm.hpp"
#include "GL/gl.h"
#include <map>
struct bin
{
glm::mat2x4 mat;
};
int main( int argc, char *argv[] )
{
std::map<char, bin> bucket;
uint16_t r = 0;
for(uint16_t n = 0; n < 7; ++n)
{
glm::vec4 v = glm::vec4(0.12128f, 0.12412f, 0.15532f, 0.23453f);
bin b;
r = 0;
b.mat[0][r++] = v.x;
b.mat[0][r++] = v.y;
b.mat[0][r++] = v.z;
b.mat[0][r++] = v.w;
r = 0;
b.mat[1][r++] = v.x;
b.mat[1][r++] = v.y;
b.mat[1][r++] = v.z;
b.mat[1][r++] = v.w;
bucket[n] = b;
}
for(auto it : bucket)
{
r = 0;
std::cout << "0:\t" << it.second.mat[0][0] << "\t" << it.second.mat[0][1] << "\t" << it.second.mat[0][2] << "\t" << it.second.mat[0][3] << "\n";
r = 0;
std::cout << "1:\t" << it.second.mat[1][0] << "\t" << it.second.mat[1][1] << "\t" << it.second.mat[1][2] << "\t" << it.second.mat[1][3] << std::endl;
}
return 0;
}
Right now I am totally lost, especially as my mwe works fine.
I am clueless what goes wrong after leaving the for-loop, so thanks for any thought on that!
Indeed, I could just rewrite that section and hope it would work - as my mwe does. But I would like to find out/ get help on finding out what exactly happens between the "assign" for loop and the "retrieve" for loop. Any ideas on that?
I made it work for me now:
Appartenly assigning the values this way:
for(auto c : alphabet::char_map)
{
c.second.face[0][n++] = c.second.offset.x;
//and so on
}
Did not work properly (for whatever reason..)
Changing this into a for(uint16_t i = 32; i < 128; ++i) worked for me. Also it was just the assigning loop, the auto-iterating ofer the map elsewhere works just fine.
The test method on the following class does not have the effect I would expect it to. I have a suspicion it is something to do with the fact that the invocation of emplace_back somehow invalidates the reference obtained via the subscript.
Either way I would expect the second print in test to result in
v[0] = 1
however both result in
v[0] = 5
suggesting that the assignment does not take place.
class FooBar {
vector<size_t> v;
public:
size_t add(size_t x) {
cout << "add(" << x << ")" << endl;
size_t K(v.size());
v.emplace_back(x);
return K;
}
void test(size_t idx) {
cout << "v[" << idx << "] = " << v[idx] << endl;
v[idx] = add(0);
cout << "v[" << idx << "] = " << v[idx]<< endl;
}
};
int main(int argc, char* argv[])
{
FooBar f;
f.add(5);
f.test(0);
}
I know that I can get around the problem by creating a temporary to store the result of add and then perform the assignment but I am interested as to why I cannot use just a straight assignment and why I do not get any kind of error when attempting to perform this.
Compiled and tested with MSVC (Visual Studio 2015).
The line
v[idx] = add(0);
is cause for undefined behavior. You are modifying the contents of v in add while assuming that v[idx] will be valid.
For predictable behavior, you can use:
void test(size_t idx) {
cout << "v[" << idx << "] = " << v[idx] << endl;
size_t val = add(0);
v[idx] = val;
cout << "v[" << idx << "] = " << v[idx]<< endl;
}