View Compilation Error

0_0_6121672_14698.cpp:3: error: expected constructor, destructor, or type conversion before ';' token
0_0_6121672_14698.cpp: In function `void f()':
0_0_6121672_14698.cpp:19: error: `b_matrix' undeclared (first use this function)
0_0_6121672_14698.cpp:19: error: (Each undeclared identifier is reported only once for each function it appears in.)