[mathcad] RE: Mathcad 7 to Mathcad 11 Problem

Author: Bruff, Stuart Posted: Mon, 10 Oct 2005 12:11:25 +0100

Bill,

The cause of the error is that the index n-m can evaluate to a negative
number - as ORIGIN=0, this isn't a valid index number.

I suspect the reason it worked in M7, but not M11, is that M7 evaluates the
conditionals (which bound n-m to lying in the interval 0..N-1) before
anything else and 'smartly' decides to return 0 before interpreting the rest
of the expression. M11, OTOH, tries to evaluate h[n-m and squawks about the
negative index.

If you correct that (by say h[|n-m|), M11 will then complain about the
attempt to reference the non-existent element h[M (the worksheet only
defines h up to h[M-1 ).

Fixing these gives the same resulta as M7.

You can also get the correct result by selecting Tools/Worksheet Options
from the menu, Calculation from the resulting dialog box, and setting
'Backward Compatibility' in Performance Preferences.

Stuart

From: Bill E Dumke "mailto:Bill.Dumke"
Sent: Friday, October 07, 2005 19:46
To: Mathcad Discussion List
Subject: [mathcad] Mathcad 7 to Mathcad 11 Problem

I was trying to get this example (Example 2.10) from "An Introduction to
Digital Signal Processing with Mathcad" to run in Mathcad 11.2a. It was
originally part of an e-book using the Mathcad 7 engine. And it works
fine using the Mathcad 7 engine supplied with the book.

Attached is a Mathcad 11.2a file. I get an error message when trying to
do the aperiodic convolution given by the expression for y.

I suspect there is a syntax difference between Mathcad 7 and 11.2a
preventing it from running.

How can I get this to run in Mathcad 11.2a?

Note that running the e-book directly from Mathcad 11.2a results in the
same error message, so I don't believe there is any error in my typing
of the expression itself.

Bill

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[mathcad] RE: Mathcad 7 to Mathcad 11 Problem

Author: Potter, Mick Posted: Mon, 10 Oct 2005 11:50:05 +0100

I think that ver7 had a shortcut method of multiplication. If it found a
zero in the expression, it didn't look any further, but just returned zero.
It wouldn't have looked at x[n-m.

I think that 11.2 checks each element, and so x[n-m is seen as out of range.

I don't think this "feature" can be switched off in 11.2, but I'd be happy
to be told otherwise.

==
Mick
|From: Bill E Dumke "mailto:Bill.Dumke"
|Sent: 7 October 2005 19:46
|To: Mathcad Discussion List
|Subject: [mathcad] Mathcad 7 to Mathcad 11 Problem
|
|I was trying to get this example (Example 2.10) from "An Introduction to
|Digital Signal Processing with Mathcad" to run in Mathcad 11.2a. It was
|originally part of an e-book using the Mathcad 7 engine. And it works
|fine using the Mathcad 7 engine supplied with the book.
|
|Attached is a Mathcad 11.2a file. I get an error message when trying to
|do the aperiodic convolution given by the expression for y.
|
|I suspect there is a syntax difference between Mathcad 7 and 11.2a
|preventing it from running.
|
|How can I get this to run in Mathcad 11.2a?
|
|Note that running the e-book directly from Mathcad 11.2a results in the
|same error message, so I don't believe there is any error in my typing
|of the expression itself.
|
|Bill
|
|______________________________________________________________________
|This email has been scanned by the MessageLabs Email Security System.
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[mathcad] RE: Mathcad 7 to Mathcad 11 Problem

Author: Potter, Mick Posted: Mon, 10 Oct 2005 12:15:38 +0100

The attached may help, but I did it quickly - check the ranges used for
summation.

==
Mick

|From: Bill E Dumke "mailto:Bill.Dumke"
|Sent: 7 October 2005 19:46
|To: Mathcad Discussion List
|Subject: [mathcad] Mathcad 7 to Mathcad 11 Problem
|
|I was trying to get this example (Example 2.10) from "An Introduction to
|Digital Signal Processing with Mathcad" to run in Mathcad 11.2a. It was
|originally part of an e-book using the Mathcad 7 engine. And it works
|fine using the Mathcad 7 engine supplied with the book.
|
|Attached is a Mathcad 11.2a file. I get an error message when trying to
|do the aperiodic convolution given by the expression for y.
|
|I suspect there is a syntax difference between Mathcad 7 and 11.2a
|preventing it from running.
|
|How can I get this to run in Mathcad 11.2a?
|
|Note that running the e-book directly from Mathcad 11.2a results in the
|same error message, so I don't believe there is any error in my typing
|of the expression itself.
|
|Bill
|
|______________________________________________________________________
|This email has been scanned by the MessageLabs Email Security System.
|For more information please visit http://www.messagelabs.com/email
|______________________________________________________________________

This e-mail plus any attachments is intended for the addressee only. The information may contain material that is confidential. If you are not the intended recipient, please notify the sender immediately and delete from any computer. Any review, disclosure, distribution, copying, use or other action in reliance on this information is prohibited.

E-mail transmission cannot be guaranteed to be secure or free from error as information can be intercepted, corrupted, lost, destroyed, arrive late or be incomplete. The sender does not therefore accept any responsibilty for errors or omissions in the content of this message.

________________________________________________________________
This message has been checked for all known viruses by the
MessageLabs Virus Control Centre. For further information visit
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Attachments:
Mathcad 7 to Mathcad 11 Problem (2).mcd

[mathcad] RE: Mathcad 7 to Mathcad 11 Problem

Author: Chris Whitford Posted: Tue, 11 Oct 2005 12:30:14 +0100

Here is another solution which doesn't involve programming. Just change the
upper limit of the summation.

Chris

At 12:15 10/10/2005 +0100, you wrote:
>The attached may help, but I did it quickly - check the ranges used for
>summation.
>
>==
>Mick
>
>|From: Bill E Dumke "mailto:Bill.Dumke"
>|
>|I was trying to get this example (Example 2.10) from "An Introduction to
>|Digital Signal Processing with Mathcad" to run in Mathcad 11.2a. It was
>|originally part of an e-book using the Mathcad 7 engine. And it works
>|fine using the Mathcad 7 engine supplied with the book.
>|
>|Bill

Attachments:
Mathcad 7 to Mathcad 11 Problem.mcd

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