Compact Finite Difference Schemes for Partial integrodifferential Equations FOURTH AND SIXTH ORDER COMPACT FINITE DIFFERENCE SCHEMES FOR PARTIAL INTEGRO-DIFFERENTIAL EQUATIONS THE NUMERICAL SOLUTION OF LNTEGRO-PARTIAL DIFFERENTIAL EQUATIONS WITH SIXTH-DEGREE B-SPLINE FUNCTIONS On The Numerical Solution of Partial integro-differential equations A comparison of Semi-analytical Methods for Solving Partial Integro- Differential Equations Compact Finite Difference Schemes for Solving a Class of Weakly- Singular Partial Integro-differential Equations