This solver interpolates data given on a regular 2D regular grid in an ASCII file (x y Value). A bilinear interpolation is used. The data in the ASCII file have to be ordered such that

x1 y1 val
x2 y1 val
...
xn y1 val
x1 y2 val
...
xn yn val 
 

The grid is describe by giving:

• (x0, y0) the left-bottom corner coordinate
• (lx, ly) the x and y lengths of the covered domain
• (Nx, Ny) the number of cells in x and y directions
• No data are given by -9999