[WP 34s] Trapezoidal approximation of area under curve

[Thomas Klemm]

(06-01-2015 01:53 PM)Marcio Wrote:  If so, I am planning on creating a program that would take advantage of that so it would be possible to easily calculate the area under a curve defined by data, as shown below:

\[ \int_{x_1}^{x_n} y(x) dx \approx \frac{1}{2} \sum_{k=1}^{n-1} (x_{k+1}-x_{k})(y_{k+1}+y_{k}) \]

You could use something like:

Code:

001 LBL'TPZ'
002 CLΣ
003 LBL 00
004 STOP
005 R↑
006 RCL+ Z
007 R↑
008 RCL- Z
009 Σ+
010 R↓
011 R↓
012 GTO 00
013 END

Usage:
\(y_1\) ENTER \(x_1\) XEQ'TPZ'
\(y_2\) ENTER \(x_2\) R/S
(...)
\(y_n\) ENTER \(x_n\) R/S
Σxy
-2 ÷

Not a sophisticated program but I hope you get the idea.

Cheers
Thomas