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Mathematics Mathematica Calculus Equation Solving Wolfram Language Numerical Computation

?NumericQ for NMaximize NIntegrate ?

Posted 11 years ago

Hi, Can you tell me what is wrong with it ? Clear[Nb] Nb[m_?NumericQ] := Table[NIntegrate[i*m, {ebar, i, (i + 1)}], {i, 1., 10}]; NMaximize[{Nb[m], 800 <= m <= 1200}, {m}] I have the following error : NMaximize::nnum: The function value {-818.293,-1636.59,-2454.88,-3273.17,-4091.46,-4909.76,-5728.05,-6546.34,-7364.63,-8182.93} is not a number at {m} = {818.293}. >> I guess the problem comes from ?NumericQ, but I must put it (or the Integrand is non numerical for NMaximize) Thank you, Mich

POSTED BY: Thibault Michel

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Posted 11 years ago

This is still an order of evaluation issue. Nb[[5]] evaluates before Nb itself does. To keep this simple, first write a function that takes in a number and outputs a single number. Then feed this to NMaximize. You could for example define Nb like this: Nb[m_?NumericQ] := Table[NIntegrate[im, {ebar, i, (i + 1)}], {i, 1., 10}][[5]] Or more concisely Nb[m_?NumericQ] := NIntegrate[5m, {ebar, 5, 6}]

POSTED BY: Sean Clarke

Posted 11 years ago

Clear[Nb] int[m_, i_] := NIntegrate[m*i, {x, i, i + 1}] Nb[m_?NumericQ] := Table[int[m, i], {i, 1., 10}]; NMaximize[{Nb[m][[5]], 800 <= m <= 1200}, {m}] Part::partw: Part 5 of Nb[m] does not exist. >> Part::partw: Part 5 of Nb[m] does not exist. >> Part::partw: Part 5 of Nb[m] does not exist. >> General::stop: Further output of Part::partw will be suppressed during this calculation. >> what about now ?