Simple grid operations

The simple grid operation are used to transform a grid in an appropriate manner. The input grid will be overwritten (destroyed). Please store or copy it to avoid it. Here are such operations:

• Set: set all cells of a selected grid to the value in P1
  remark: also the no-data values
• Exchange: exchanges in a selected grid the values in P1 with the values in P2
  remark: this is useful to change no-data values to a new one or reverse
• Rand: fills a selected grid with random values, if a the number of rows in P1 and the number of cols are given in P2, then a new grid filled with random values will be constructed
• Add: adds the value in P1 to all grid cells
  remark: if the value is negative, so a difference will be calculated
• Mul: multiplies the value in P1 with all grid cells
• Log: calculates the Briggs logarithm of all grid cells (all grid cells must be != 0)
• Abs: calculates the absolute values of all grid cells
• Norm: transforms the values in the range between [0..1]
• Norm+-3Std: a variant of normalize it cuts all values bigger than +-3std (standard deviation)
• Norm_Standard normalizes the grid using (x-mean)/std std=standard deviation remark this is a very useful normalization from the statistics
• Inv: inverts all grid cells using g[i][j]:=Max-g[i][j]
• Cut: cut off all values P1 and P2, if P3 is given, than all values between P1 and P2 will be set to P3
• Cut Off: eliminates all values between P1 and P2 and optionally replaces it with P3
• Cut_Fuzzy: a variant of cut, sets all values greater P2 to P2
• Class: classifies all values between P1 and P2 with a step in P3
• Quad: evaluates a quadratic equation P1*x^2+P2*x+P3 to all grid cells
• Tanh: applies tanh(a*(x-x0))+c with P1:a P2:x0 P3:c
• Gauss: applies a gaussian function: exp(-x^2/s^2) with P1:s^2