Re: How to solve the integrate problem

*To*: mathgroup at smc.vnet.net*Subject*: [mg128139] Re: How to solve the integrate problem*From*: Alexei Boulbitch <Alexei.Boulbitch at iee.lu>*Date*: Tue, 18 Sep 2012 03:42:39 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net

x>Q ,Q(P-W)-M(x-Q), x belongs(Q,infinite) x<=Q,P*x-W*Q+S(Q-x), x belongs(0,Q) Q,P,W,M,S are unknown constant number. I want to *dx* THANK U It is not very clear, what do you mean by "I want to *dx*". If you need to integrate your expression, try this: (* This is your function *) f[x_] := If[x > Q, Q (P - W) - M (x - Q), P*x - W*Q + S (Q - x)] (* Here it is drawn with arbitrarily selected values of its parameters to see, how it looks like *) Plot[f[x] /. {Q -> 1, P -> 2, W -> 1, M -> 1.5, S -> 3}, {x, 0, 3}] (* Here the integral is calculated. It is a piecewise function and its value depends upon the value of Q *) (* as well as upon the value xmax *) Manipulate[ Integrate[f[x], {x, 0, xmax}, Assumptions -> Q >= 0], {xmax, 0, 2}] If you want to calculate the derivative, consider this: D[f[x], x] If[x > Q, -M, P - S] Have fun, Alexei Alexei BOULBITCH, Dr., habil. IEE S.A. ZAE Weiergewan, 11, rue Edmond Reuter, L-5326 Contern, LUXEMBOURG Office phone : +352-2454-2566 Office fax: +352-2454-3566 mobile phone: +49 151 52 40 66 44 e-mail: alexei.boulbitch at iee.lu