链接器错误：架构x86_64的重复符号

Question

我有一个header1.h包含在raster2d.h中，然后raster2d.h包含在io.cpp和raster2d.cpp中。当我编译时，我得到以下链接器错误`

   g++ -g -I. -I/opt/local/include  -o raster2d.o -c raster2d.cpp
   g++ -g -I. -I/opt/local/include  -o stb.o -c stb.cpp
   g++ -g -I. -I/opt/local/include  -o io.o -c io.cpp
   g++ -o raster2d raster2d.o SimpleImage.o stb.o io.o  -L/opt/local/lib  
   duplicate symbol __ZN9Transform14multiplicationE6Matrix in:
       raster2d.o
       io.o
   duplicate symbol __ZN9Transform5scaleEP7Point2fff in:
       raster2d.o
       io.o
   duplicate symbol __ZN9Transform6rotateEP7Point2ff in:
       raster2d.o
       io.o
   duplicate symbol __ZN9Transform9translateEP7Point2fff in:
       raster2d.o
       io.o
   ld: 4 duplicate symbols for architecture x86_64
   clang: error: linker command failed with exit code 1 (use -v to see invocation)
   make: *** [raster2d] Error 1

Transform是header.h中的一个类 Transform :: translate Transform :: scale＆amp; Transform :: rotate是header1.h

中的三个函数