lets suppose , in attach file its acceleration file data downloaded from peer , it will used in nonlinear time history , but for IDA i have to find scale factor(SF , and multiply SF with acceleration ???  

Scale factor =  o.05*g/max(abs(a))

IDA = scale factor * acceleration file data 

so is this the right ???

so difference between nonlinear time history and IDA is only that "scale factor "  ... please explain