﻿ Sample Problems > Usage > Misc > save

# save

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# save   { SAVE.PDE

This example illustrates use of the SAVE function.

SAVE(F) computes the value of F at each mesh node, and returns interpolated

values for any position within a cell.

If  F is very expensive to compute, the use of SAVE can reduce the overall cost

of a simulation.

SAVE also hides the complexity of F from differentiation in forming the coupling

matrix, and may therefore avoid numerical difficulties encountered in computing

the derivatives of pathological functions.

}

title 'SAVE test'

select

ngrid=20

contourgrid=100 { use a very dense plot grid to show data structure }

Variables

u,v

definitions

k = 2

u0 = 1+x^2+y^2

s = cos(20*x)*cos(20*y)

save_s = save(s)       { Used in a definition }

Initial values

u = 1

equations

U: u - div(K*grad(u))  = s

V: v - div(K*grad(v))  = save_s

boundaries

region 1

start(-1,-1)

value(u)=u0 value(v)=u0

line to (1,-1) to (1,1) to (-1,1) to close

region 2

k=4

start(-1,-1) line to (0,-1) to (0,0) to (-1,0) to close

plots

grid(x,y)

contour(u)

contour(v)

contour(s)

contour(save_s)

elevation(s, save_s) from(-1,0) to (1,0)

end