1. Department of Applied Mathematics and Scientific Computing , Indian Institute of Technology Roorkee-IIT Roorkee, Roorkee 247667 , India
2. Department of Mathematics, Indian Institute of Technology Roorkee-IIT Roorkee , Roorkee 247667 , India
3. Department of Applied Mathematics and Scientific Computing, Indian Institute of Technology Roorkee-IIT Roorkee , Roorkee 247667 , India