On redbook, pp.673, description of rotaion matrices is confusing:
a of glRotatef*(a, 1, 0, 0) is degree, so glRotatef*(a, 1, 0, 0) is not equal to rotaion matrix using a. (redbook uses : instead of equation, but still very confusing. Some people helped me my confusion on the board)
glRotatef*(a, 1, 0, 0) is equal to the rotation matrix using a*3.1415,/180 (radian) , this should be clear in the book.