well I wanted to write a mathematica program so i can be able to experiment but for some reason i cant get it to work, does anybody have any ideas on where im going wrong, below is something that i have cut out of my mathematica program, all you have to do is cut and paste into mathematica

please help

thank you

\!\(\(LowerRiemann[a0_, b0_,

n0_] := \[IndentingNewLine]Module[{a = a0, b = b0, n = n0,

X}, \[IndentingNewLine]\[IndentingNewLine]X\_i_ =

a + i\ \(b - a\)\/n\ ; \ \[IndentingNewLine]sum =

0; \[IndentingNewLine]For[\[IndentingNewLine]i = 1,

i <= n, \(i++\), \[IndentingNewLine]Xv =

Select[Xvals,

X\_\(i - 1\) <= #1 <= X\_i\ &]; \[IndentingNewLine]Ymin = \

Min[f[Xv]]; \ \[IndentingNewLine]sum =

sum + Ymin\ \(b - a\)\/n;\ \ \[IndentingNewLine]]; \ \

\[IndentingNewLine]Return[\ \ sum\ ];\ ];\)\ \[IndentingNewLine]

\(f[x_] = x\^2;\)\[IndentingNewLine]

\(a = 0;\)\[IndentingNewLine]

b = 1; \[IndentingNewLine]

\(n = 25;\)\[IndentingNewLine]

LowerRiemann[a, b, n]\)