Write slopes vector in pfb

[mvhulten]

For now use Nicolas' burning routine.

Then save slopes (2 coordinates) in the ParFlow binary format (.pfb) with

slopex, slopey = grid.grad
write_pfb('slopex.pfb', slopex)
write_pfb('slopey.pfb', slopey)

edit: this^ code sketches the idea but is wrong (Grid.grad and write_pfb() do not exist).

[mvhulten]

The only slope function in ParFlow seems to be the function object cell_slopes(). The problems with this are

• It returns a scalar the slope between each cell and its downstream neighbour, instead of a vector
• It does d8, dinf and mfd only and not d4, at least it does not recognise routing=d4

I asked about this upstream.