In[]:=
​​​​​​intsom[f_,n_,a_,b_]:=Module[{t=0,fen={}},​​While[t<n+1,​​c=f[a+((b-a)/n)*t];​​fen=Append[fen,c];​​t++​​];​​T=((b-a)/n)*(Total[fen]-0.5*(f[a]+f[b]));​​Return[N[T]]​​];​​g[x_]:=x^2​​
In[]:=
​​list1={};​​list2={};​​​​Do[list1=Append[list1,Abs[39-intsom[g,20*n,2,5]-(intsom[g,20*n,2,5]-intsom[g,10*n,2,5])/3]],{n,10,100}]​​ListPlot[list1]​​​​intsom[g,100,2,5]
Out[]=
0
20
40
60
80
2.0×
-15
10
4.0×
-15
10
6.0×
-15
10
8.0×
-15
10
1.0×
-14
10
1.2×
-14
10
Out[]=
39.0005
In[]:=
​​
​
In[]:=
​
​