Editing Guide to madagascar programs (section)

==sfstack==
{| class="wikitable" align="center" cellspacing="0" border="1"
! colspan="4" style="background:#ffdead;" | Stack a dataset over one of the dimensions.
|-
! colspan="4" | sfstack < in.rsf > out.rsf scale= axis=2 rms=n norm=y min=n max=n prod=n
|-
|  colspan="4" | <br>This operation is adjoint to sfspray.
|-
| ''int    '' || '''axis=2''' ||   || 	which axis to stack. If axis=0, stack over all dimensions
|-
| ''bool   '' || '''max=n''' ||  [y/n] || 	If y, find maximum instead of stack.  Ignores rms and norm.
|-
| ''bool   '' || '''min=n''' ||  [y/n] || 	If y, find minimum instead of stack.  Ignores rms and norm.
|-
| ''bool   '' || '''norm=y''' ||  [y/n] || 	If y, normalize by fold.
|-
| ''bool   '' || '''prod=n''' ||  [y/n] || 	If y, find product instead of stack.  Ignores rms and norm.
|-
| ''bool   '' || '''rms=n''' ||  [y/n] || 	If y, compute the root-mean-square instead of stack.
|-
| ''floats '' || '''scale=''' ||   || 	optionally scale before stacking  [n2]
|}

While <tt>sfspray</tt> adds a dimension to a hypercube,
<tt>sfstack</tt> effectively removes one of the dimensions by stacking
over it. Here are some examples:
<pre>
bash&#36; sfmath n1=5 n2=3 output=x1+x2 > test.rsf
bash&#36; < test.rsf sfdisfil
   0:             0            1            2            3            4
   5:             1            2            3            4            5
  10:             2            3            4            5            6
bash&#36; < test.rsf sfstack axis=2 | sfdisfil
   0:           1.5            2            3            4            5
bash&#36; < test.rsf sfstack axis=1 | sfdisfil
   0:           2.5            3            4
</pre>
Why is the first value not 1 (in the first case) or 2 (in the second
case)? By default, <tt>sfstack</tt> normalizes the stack by the fold
(the number of non-zero entries). To avoid normalization, use
<tt>norm=n</tt>, as follows:
<pre>
bash&#36; < test.rsf sfstack norm=n | sfdisfil 
   0:             3            6            9           12           15
</pre>
<tt>sfstack</tt> can also compute root-mean-square values as 
well as minimum and maximum values.
<pre>
bash&#36; < test.rsf sfstack rms=y | sfdisfil
   0:         1.581         2.16        3.109        4.082        5.066
bash&#36; < test.rsf sfstack min=y | sfdisfil
   0:             0            1            2            3            4
bash&#36; < test.rsf sfstack axis=1 max=y | sfdisfil 
   0:             4            5            6
</pre>