Thanks Luc, thanks for getting back so quickly, and will wait for your information tomorrow. -sujit On Mar 30, 2012, at 2:36 PM, Luc Maisonobe wrote: > > > > SUJIT PAL a écrit : > >> Hi, >> >> I have a (newbie) question about how to go about solving the problem >> below with commons-math. >> >> 1) I have histogram data (equal x intervals) based off some >> distribution. >> 2) I need a way to calculate the second differential between two given >> x points in the distribution. >> >> Here is what I think I should do: >> 1) Feed the (x,y) values represented by the top of each histogram entry >> within my x-range into a UnivariateRealInterpolator between ranges >> (x1,y1) and (x2,y2). >> 2) The interpolate method gives me back a PolynomialSplineFunction >> (call if psf). >> 3) I get the second differential UnivariateRealFunction (call it urf) >> by calling psf.getPolynomialSplineDerivative().derivative() >> 4) I compute the second derivative value as the difference of >> urf.value(x2) - urf.value(x1) >> >> Does this sound like a reasonable/accurate approach? Any >> suggestions/gotchas or pointers to better approaches? > > No, this is not an approach I would recommend. A much more straightforward > way to compute this derivative is to apply a dedicated finite differences formula > on three consecutive points. I'll give ou such a formula tomorrow (I am on a mobile > device right now and it is difficult to write a complète mail...) > > Luc > >> >> Thanks very much, >> >> Sujit >> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: user-unsubscribe@commons.apache.org >> For additional commands, e-mail: user-help@commons.apache.org > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: user-unsubscribe@commons.apache.org > For additional commands, e-mail: user-help@commons.apache.org > --------------------------------------------------------------------- To unsubscribe, e-mail: user-unsubscribe@commons.apache.org For additional commands, e-mail: user-help@commons.apache.org