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@ -38,35 +38,23 @@
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! File: ppde.f90
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!
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! Program: ppde
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! This sample program shows how to build and solve a sparse linear
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!
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! The program solves a linear system based on the partial differential
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! equation
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!
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! This sample program solves a linear system obtained by discretizing a
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! PDE with Dirichlet BCs.
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!
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!
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! The equation generated is
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!
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! b1 d d (u) b2 d d (u) a1 d (u)) a2 d (u)))
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! - ------ - ------ + ----- + ------ + a3 u = 0
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! dx dx dy dy dx dy
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!
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!
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! with Dirichlet boundary conditions on the unit cube
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! The PDE is a general second order equation in 3d
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!
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! 0<=x,y,z<=1
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!
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! The equation is discretized with finite differences and uniform stepsize;
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! the resulting discrete equation is
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! b1 dd(u) b2 dd(u) b3 dd(u) a1 d(u) a2 d(u) a3 d(u)
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! - ------ - ------ - ------ - ----- - ------ - ------ + a4 u = 0
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! dxdx dydy dzdz dx dy dz
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!
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! ( u(x,y,z)(2b1+2b2+a1+a2)+u(x-1,y)(-b1-a1)+u(x,y-1)(-b2-a2)+
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! -u(x+1,y)b1-u(x,y+1)b2)*(1/h**2)
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! with Dirichlet boundary conditions, on the unit cube 0<=x,y,z<=1.
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!
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! Example taken from: C.T.Kelley
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! Example taken from:
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! C.T.Kelley
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! Iterative Methods for Linear and Nonlinear Equations
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! SIAM 1995
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!
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!
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! In this sample program the index space of the discretized
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! computational domain is first numbered sequentially in a standard way,
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! then the corresponding vector is distributed according to a BLOCK
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@ -75,7 +63,9 @@
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! Boundary conditions are set in a very simple way, by adding
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! equations of the form
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!
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! u(x,y) = rhs(x,y)
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! u(x,y) = exp(-x^2-y^2-z^2)
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!
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! Note that if a1=a2=a3=a4=0., the PDE is the well-known Laplace equation.
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!
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program ppde
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use psb_base_mod
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