Need help simplifying final expression

Question

I was carrying out a function and ended up with the desired answer, but for some reason, Mathematica keeps giving me the answer in a strange numerical form.

SIMP[a_, b_, n_] := (1/3)[(b - a)/n][
  Sum[f[a + (2 x - 2) (b - a)/n] + 4 f[a + (2 x - 1) (b - a)/n] + 
    f[a + 2 x (b - a)/n], {x, 1, n/2}]]

SIMP[0, 2, 8]
(* (1/3)[1/4][
 f[0] + 4 f[1/4] + 2 f[1/2] + 4 f[3/4] + 2 f[1] + 4 f[5/4] + 
  2 f[3/2] + 4 f[7/4] + f[2]] *)

Clear[f]
f[x_] := 1/(1 + x^6)
SIMP[0, 2, 8]
(* (1/3)[1/4][557032465187652359/44540986037769325] *)

All I need is for the output to turn into a numerical value with 6 decimal places, but it stays in this form. Any advice?

Please take a look at other Simpson integrators. For example here, but there are a lot around — Dr. belisarius, Oct 24 '15 at 03:20
Welcome to Mathematica.SE! I suggest the following: 0) Browse the common pitfalls question 1) As you receive help, try to give it too, by answering questions in your area of expertise. 2) Read the [faq]! 3) When you see good questions and answers, vote them up by clicking the gray triangles, because the credibility of the system is based on the reputation gained by users sharing their knowledge. Also, please remember to accept the answer, if any, that solves your problem, by clicking the checkmark sign! — Dr. belisarius, Oct 24 '15 at 04:58
You should use square brackets only to group arguments of functions and not as parentheses. — Sjoerd C. de Vries, Oct 24 '15 at 21:00

score 3 · Accepted Answer · answered Oct 24 '15 at 03:11

3

ClearAll[f,sIMP];
sIMP[a_, b_, n_] := (1/3) ((b - a)/n) 
          Sum[ f[a + (2 x - 2) (b - a)/n] + 4 f[a + (2 x - 1) (b - a)/n] + 
               f[a + 2 x (b - a)/n], {x, 1, n/2}]
f[x_] := 1/(1 + x^6)
sIMP[0, 2, 8] // N

(* 1.0421720807799113` *)

answered Oct 24 '15 at 03:11

Dr. belisarius

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Square brackets and parentheses are different beasts in Mathemtica – Dr. belisarius Oct 24 '15 at 03:11

Need help simplifying final expression

1 Answers1