Consider the array d: d = linspace( -10, 10, 10 ) If I want to multiply every value above -5 by 100 I can do d[ d>-5 ] *= 100 But what if I want to multiply every value between -5 and +5 by 100. This does NOT work: d[ d>-5 and d<5 ] *= 100 Any ideas? Thanks, Mark