未能获得磁偏角

问：

我正在尝试运行一个代码，以便在 GeographicLib 库正在访问的世界磁模型的数据的帮助下获取磁偏角的值。 但是，由于多个错误，编译失败。"undefined reference to"

背景：

1. 地理库已提取到默认位置/usr/local
2. 用于运行代码的 IDE 是 Geany
3. 在 Raspberry Pi 4 上运行，Raspbian 启动
4. 尝试通过 bash 终端运行的命令 =

(a) g++ work_cpp.cpp -o p 
(b) g++ work_cpp.cpp wmm.h -o p

5. 尝试通过 IDE 本身构建 =

 g++ -Wall -o "work_cpp" "work_cpp.cpp" (in directory: /home/pi/Desktop/picodes)

我尝试了一些方法，但到目前为止它们都不起作用：

1. sudo 将 sbin 和 geographicLib 的文件从/usr/local/usr/bin

2. sudo 将头文件复制到库的位置，即/usr/include

/usr/local/include/GeographicLib 

作为一个新手，我被这些未定义的错误所淹没，我迫切希望得到答案和运行我的代码。

代码如下：

work_cpp.cpp

#include<iostream>
#include "wmm.h"

int main(){
    std::cout<<"starting...\n\r"<<std::endl;
    wmm * magnetic_model = new wmm();
    std::cout<<"\033[2J\033[?25l"<<std::endl;
    while(1){
        magnetic_model->update(19.07283,72.88261,10);
        std::cout<<"\033[0;0H"<<std::endl;
        std::cout<<"Declination: %2.3f\n\r"<<magnetic_model->declination()<<std::endl;
        }
        delete magnetic_model;
    return 0;}

wmm.h

#ifndef __WMM_H__
#define __WMM_H__
#include <GeographicLib/MagneticModel.hpp>
using namespace GeographicLib;
class wmm
{
private:
    double magnetic_declination;
    double magnetic_inclination;
    double field_strength;

public:
    double declination();
    double inclination();
    double strength();
    void update(float lat, float lon, float alt);
};
#endif
void wmm::update(float lat, float lon, float alt)
{
    double Bx, By, Bz, H;
    time_t t = time(NULL);
    tm* timePtr = localtime(&t);
    MagneticModel mag("emm2015");
    mag(timePtr->tm_year + 1900, lat, lon, alt, Bx, By, Bz);
    MagneticModel::FieldComponents(Bx, By, Bz, H, field_strength, magnetic_declination, magnetic_inclination);
}

错误信息：

g++ -Wall -o "work_cpp" "work_cpp.cpp" (in directory: /home/pi/Desktop/picodes)
/usr/bin/ld: /tmp/ccEL2G3m.o: in function `wmm::update(float, float, float)':
work_cpp.cpp:(.text+0x7c): undefined reference to `GeographicLib::Geocentric::WGS84()'
/usr/bin/ld: work_cpp.cpp:(.text+0xa4): undefined reference to `GeographicLib::MagneticModel::MagneticModel(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, GeographicLib::Geocentric const&, int, int)'
/usr/bin/ld: /tmp/ccEL2G3m.o: in function `main':
work_cpp.cpp:(.text+0x288): undefined reference to `wmm::declination()'
/usr/bin/ld: /tmp/ccEL2G3m.o: in function `GeographicLib::MagneticModel::operator()(double, double, double, double, double&, double&, double&) const':
work_cpp.cpp:(.text._ZNK13GeographicLib13MagneticModelclEddddRdS1_S1_[_ZNK13GeographicLib13MagneticModelclEddddRdS1_S1_]+0x6c): undefined reference to `GeographicLib::MagneticModel::Field(double, double, double, double, bool, double&, double&, double&, double&, double&, double&) const'
/usr/bin/ld: /tmp/ccEL2G3m.o: in function `GeographicLib::MagneticModel::FieldComponents(double, double, double, double&, double&, double&, double&)':
work_cpp.cpp:(.text._ZN13GeographicLib13MagneticModel15FieldComponentsEdddRdS1_S1_S1_[_ZN13GeographicLib13MagneticModel15FieldComponentsEdddRdS1_S1_S1_]+0x70): undefined reference to `GeographicLib::MagneticModel::FieldComponents(double, double, double, double, double, double, double&, double&, double&, double&, double&, double&, double&, double&)'
collect2: error: ld returned 1 exit status
Compilation failed.