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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)
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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.
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11, rue Edmond Reuter,
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Office phone :  +352-2454-2566
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e-mail: alexei.boulbitch at iee.lu






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