1997 Ulrik Kjems, DSP/IMM, Technical University of Denmark, uk@imm.dtu.dk
Use : 

 ivar [-i level] [-l scalelist] [-m maskfile] [-o variancevol] [-s meanvol]
         file1 file2 ... fileN 

Computes variance image between the specified volumes.
'outfile' is the variance image of file1..fileN

The input 'maskfile' tells ivar which voxels to calculate sum for. The variance 
is set to 0 for voxels where maskfile is 0. 

'outputmean' specifies where to save the computed mean image. 

'scalelist' is an ASCII string containing 1 float per volume (sep by spaces).
Each volume in the list is multiplied with this scaling factor before the
mean and variance volumes are computed.

'level' is the report level, either 'silent', 'info' or 'std'. 

All volumes have to have same size. Computations are made in double precision.