How shift the triangle shape vector from matrix ? continues moving elements wise?

How shift or move the triangle shape vector by position wise horizontal wis from matrix ?

 M=[   14     0    40     0    66    68     0    94     0   120     0
     0   119    11    13    26    39    52    65    93   106     0
     0     0    64     0   118     0    12     0    38     0     0
     0     0     0    22    24    37    50    63     0     0     0
     0     0     0     0    36    49    62     0     0     0     0
     0     0     0     0     0    61     0     0     0     0     0
     0     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     0     0     0     0     0     0     0]