Integrate question
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10-19-2017, 03:08 PM
Post: #14
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RE: Integrate question
I like your analysis!
However, (and this part is the same as my last post): [CAS] a:=int(cos(2*x)^3*sin(2*x)^5,x); // From the original example, [CAS] var a becomes: -3*cos(2*x)^8+8*cos(2*x)^6-6*cos(2*x)^4)/48 b:=-(3*sin(2*x)^8-4*sin(2*x)^6)/48; // result obtained by hand, (and wxMaxima) Now try this: subst(a,x = 0.58)-subst(b,x = 0.58); // difference =ā2.08333333333eā2 This demonstrates that they do not produce the same result, regardless of the difference being a constant, (OR any constant being valid for an indefinite integral). Also, by hand, or the wxMaxima result is better than the CAS/xcas result, in that it recognizes that you can use ANY constant, not just one particular constant offered up by CAS, (-1/48, in this case). Notice, these are simply 'as entered' examples, (no massaging attempts to format the results, this time). There is a constant bias on the [CAS] side, which needs to be modeled, if simulating a PLC, for example. The constants accumulate with multi-processing, so the output routine must chase the resulting error term. -Dale- |
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