# Sasanka Roy

We study new types of geometric query problems defined as follows: given a geometric set P , preprocess it such that given a query point q, the location of the largest circle that does not contain any member of P , but contains q can be reported efficiently. The geometric sets we consider for P are boundaries of convex and simple polygons, and point sets.(More)
This technical note is concerned with finite frequency negative imaginary (FFNI) systems. Firstly, the concept of FFNI transfer function matrices is introduced, and the relationship between the FFNI property and the finite frequency positive real property of transfer function matrices is studied. Then the technical note establishes an FFNI lemma which gives(More)
• Comput. Geom.
• 2005
Given a polyhedral terrain with n vertices, the shortest monotone descent path problem deals with finding the shortest path between a pair of points, called source (s) and destination (t) such that the path is constrained to lie on the surface of the terrain, and for every pair of points p = (x(p), y(p), z(p)) and q = (x(q), y(q), z(q)) on the path, if(More)
• J. Discrete Algorithms
• 2010
A path from s to t on a polyhedral terrain is descending if the height of a point p never increases while we move p along the path from s to t. No efficient algorithm is known to find a shortest descending path (SDP) from s to t in a polyhedral terrain. We give two approximation algorithms (more precisely, FPTASs) that solve the SDP problem on general(More)
• CCCG
• 2008
Given a set of n points P = {p1, p2, . . . , pn} in the plane, we show how to preprocess P such that for any query line segment L we can report in O(log n) time the smallest enclosing circle whose center is constrained to lie on L . The preprocessing time and space complexity are O(n log n) and O(n) respectively. We then show how to use this data structure(More)
In the map labeling problem, we are given a set P = {p1, p2, . . . , pn} of point sites distributed on a 2D map. The label of a point pi is an axis-parallel rectangle of specified size. The objective is to label maximum number of points on the map so that the placed labels are mutually non-overlapping. Here, we investigate a special class of map labeling(More)
• Comput. Geom.
• 2013
A new class of geometric query problems are studied in this paper. We are required to preprocess a set of geometric objects P in the plane, so that for any arbitrary query point q, the largest circle that contains q but does not contain any member of P , can be reported efficiently. The geometric sets that we consider are point sets and boundaries of simple(More)