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G
GerritBarrere1-Visitor
1-Visitor
September 9, 2011
Question

Strange convolution results

  • September 9, 2011
  • 6 replies
  • 4243 views

When I try to convolve simple vectors in Prime I get what looks like complex number noise in the result. For example:

This looks like a bug to me. What's up?

6 replies

M
MikeArmstrong1-Visitor
1-Visitor
September 9, 2011

I can't see the image, can you upload it again or post the worksheet.

Mike

V
VladimirN24-Ruby III
24-Ruby III
September 10, 2011

Mathcad Prime file can be found in this thread:
http://communities.ptc.com/message/167675

P.S. I have no access to the Prime right now, so I do not see what the problem is.

M
MikeArmstrong1-Visitor
1-Visitor
September 12, 2011

Why are you cross threading?

Mike

M
MikeArmstrong1-Visitor
1-Visitor
September 12, 2011

Change the formatting from General to Decimal that should sort it.

Mathcad Prime 1.0 has double point floating point precision. It's not possible to represent some numbers, due to rounding errors.

Mike

V
VladimirN24-Ruby III
24-Ruby III
September 12, 2011

Mike,

You are attached to the message file created for the version of Prime 2.0.

M
MikeArmstrong1-Visitor
1-Visitor
September 12, 2011

Mike,

You are attached to the message file created for the version of Prime 2.0.

Oops, good spot.

Mike

R
RichardJ19-Tanzanite
19-Tanzanite
September 12, 2011

Please do not cross post.

The very small non-zero numbers are just numerical roundoff error.

V
VladimirN24-Ruby III
24-Ruby III
September 12, 2011

Recently had a discussion about it: http://communities.ptc.com/message/167388#167388

G
GerritBarrere1-VisitorAuthor
1-Visitor
September 12, 2011

Thanks for the helpful responses. Sorry about the mutiple posts -- they were being refused all day but were apparently backing up.

I guess the answer is to format results appropriate for the problem. I will experiment with this.

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