Hello all,

Is it possible to have access to data keyed into the calc using the \(\sum +\) for other procedures other than stat functions? 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:

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

Many thanks

Marcio

(06-01-2015 01:53 PM)Marcio Wrote: [ -> ]Is it possible to have access to data keyed into the calc using the \(\sum +\) for other procedures other than stat functions?

The SUMS catalog has all the accumulated data ready for access. All commands in this catalog are programmable.

(06-01-2015 03:54 PM)Marcus von Cube Wrote: [ -> ] (06-01-2015 01:53 PM)Marcio Wrote: [ -> ]Is it possible to have access to data keyed into the calc using the \(\sum +\) for other procedures other than stat functions?

The SUMS catalog has all the accumulated data ready for access. All commands in this catalog are programmable.

The problem is that the trapezoidal approximation appears to require the individual data points, and not just the sums. You'll probably have to write a custom program that accumulates its own sums, either on the fly, or by using a block of registers to store x and y data points.

(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

Works like a charm.

Thank you

(06-01-2015 06:56 PM)Thomas Klemm Wrote: [ -> ]Not a sophisticated program but I hope you get the idea.

A bit of sophistication can be added by using the 34s' complex functions:

Code:

`01 LBL"TRP"`

02 CLΣ

03 CLSTK

04 STOP

05 LBL 01

06 STOP

07 cplx x<> Z

08 +/-

09 cplx RCL+ Z

10 Σ+

11 cplx DROP

12 GTO 01

XEQ"TRP"

y1 ENTER x1 R/S

y2 ENTER x2 R/S

...

Σxy 2 ÷
Dieter

Hello again,

Does anyone know how to do \(RCL+ Z\) on the 35s? From what I saw in the manual, one has to use the EQN inside the program in order to recall the \(z\)-register, which is somewhat dangerous.

Thanks.

(06-16-2015 10:47 AM)Marcio Wrote: [ -> ]Does anyone know how to do \(RCL+ Z\) on the 35s?

Yes. You can't. Recall-arithmetics is not available for the stack registers.

Of course you can do a RCL+Z with

variable Z, but that's a completely different story.

Dieter

(06-16-2015 10:47 AM)Marcio Wrote: [ -> ]Does anyone know how to do \(RCL+ Z\) on the 35s?

You can use the following program:

Code:

`T001 LBL T`

T002 CLΣ

T003 STOP

T004 REGY+REGT

T005 REGY-REGT

T006 Σ+

T007 R↓

T008 R↓

T009 GTO T003

Usage:

\(y_1\) ENTER \(x_1\) XEQ T

\(y_2\) ENTER \(x_2\) R/S

(...)

\(y_n\) ENTER \(x_n\) R/S

Σxy

2 ÷

Cheers

Thomas

Thank you Thomas.

I myself created a program with more than 2 times as many lines as yours, which is not only simpler but also much more elegant.

Very much appreciated.

Marcio