1-Visitor

Question

Possible bug? - Vector square root vs raise to power of 0.5

Forum|Forum|11 years ago
September 3, 2014
9 replies
3838 views

For some reason, the square root symbol works but raising to a power of 0.5 doesn't:

Version: 15.0

Mathcad doc attached.

1_Square-Root-Issue-xmcd.zip

Algebra_Geometry

M

MikeArmstrong

1-Visitor

Remove the units from a and b.

M

MikeArmstrong

1-Visitor

Might be worth reading this:

Werner_E

25-Diamond I

Good information, but I am not sure if it relates to the problem here.

After all without vectorization all is working as expected.

A

AlanStevens

19-Tanzanite

Mathcad doesn't treat row vectors as true vectors, so best to use column vectors:

Alan

D

Dan888

Author

1-Visitor

Thanks, my actual vectors are quite long and look better in the worksheet as row vectors.

The square root works so I'll continue but it does seem that there is a bug in there.

Update, just played a bit more and it appears to be the decimal causing the problem. 0.5 fails but 1/2 works.

A

AlanStevens

19-Tanzanite

You could just write them as row vectors, but put a transpose at the end:

e.g. a = (1 2 3)ctrl_1

Alan

Werner_E

25-Diamond I

Dan Rose wrote:
For some reason, the square root symbol works but raising to a power of 0.5 doesn't:

Thats a bit strange and I tend to call it a bug - at least I agree that it should work as you expected when we use column vectors.

The problem seems to be the combination of units and vectorization and the error is thrown with column and rowvectors alike.

Interestingly it works if you replace 0.5 by 1/2 and it also works with symbolic evaluation.

As Alan already noted it also works when we place the vecorization operator inside and use column vecctors.

1_Square-Root-Issue_WE_1-xmcdz.zip

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