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Re: Integrating a Piecewise function four times but different results

• To: mathgroup at smc.vnet.net
• Subject: [mg121787] Re: Integrating a Piecewise function four times but different results
• From: Gabriel Landi <gtlandi at gmail.com>
• Date: Sun, 2 Oct 2011 02:36:25 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• References: <201110010708.DAA17775@smc.vnet.net>

This really seems like a bug. T
he problem is on the integration of p2. If you  first do the integration of p1 first and then substitute the values you get the correct answer. 

soln2[x_] =
 Integrate[Integrate[Integrate[Integrate[p1[x], x], x], x], x] + r*x^3 +
    s*x^2 + u*x + v /. wmax -> 1 /. L -> 1

Moreover, it gives the wrong answer because the function is defined piecewise. For instance,

Integrate[Integrate[Integrate[Integrate[2 (1 - x), x], x], x], x]

obviously gives the correct result.

• References:
  • Integrating a Piecewise function four times but different results
    • From: "Rob Y. H. Chai" <yhchai@ucdavis.edu>