[R] How to control height of abline

I use matplot to get the density curve and then I use abline(v=g$V2, col = 3 ) to get the vertical line. Goal : I want very small lines at the bottom on the x axis , if possible in the arrow forms instead of vertical lines on the whole graph. Thanks a lot. [[alternative

[R] Reg : using two different matrix : how to do t.test

I have two matrix with same dimensions. I want to do t.test using each column from 2 different matrix. Row n Column names in both matrix are same. e.g. Matrix1 id VC1 VC2 VC3 R 1 2 3 R1 4 5 6 R3 7 8 9 Matrix2 id VC1 VC2 VC3 R 10 11 12 R1 13 14 15 R3 16 17