I want to sketch a piecwise constant function. ie S(t) on y axis, time on x axis. The values of S(t) are arbitrary, i just want a piecwise constant function with time partition 1/10 to use in my presentation.eg: S(t)=10 for  0≤t<1/10 S(t)=3 for   1/10≤t<2/10 and so forth up to t=1. I  want to have a closed circle at the left endpoint and an open one at the right endpoint to indicate the discontinuity, ie open circle at t=0, closed circle at t=1/10 for S(t)=10,and a line connecting the two points, open circle at t=1/10 for S(t)=3 open cicle at t=2/10 and so forth. I can't figure out how to do this. I then need to  insert it into my beamer presentation which I've also never done before. I have been unable to figure this out in the last hour so have continued with the rest of my presentation and left this bit.