If statement using a vector
3

Question

If statement using a vector

1clown (Mechanical)

(OP)

19 Sep 11 21:16

Hi Guys, I need to use an if statement and one of the inputs is a vector and I cannot get it to work.
I have an equation like this

Z:=if(C*D > min(A,B),min(A,B),C*D)

Where C and D are both vectors.
The message I get is that they need to be scalar quantities. I have tried converting A & B into vectors and using a basic program but no luck.
Any help would be appreciated.
Thanks

Occupant (Mechanical) · Answer 1 · 2011-09-20 05:23:06

If you mean by that what's in the picture, then it works just fine, no scalar required.

http://files.engineering.com/getfile.aspx?folder=e01b2c72-85e6-4480-aab5-7a

jghrist (Electrical) · Answer 2 · 2011-09-20 08:45:44

If C & D are vectors of the same length and A and B are scalar, it should work. See attached.

http://files.engineering.com/getfile.aspx?folder=319732fc-291e-475f-8bbb-d4

1clown (Mechanical) · Answer 3 · 2011-09-20 16:23:22

Hi Guys thanks for the answers. I still cannot get this to work. I have tried examples like yours and they work fine.
I did discover that one of my values that I thought was a vector was actually a scalar number.I have a min function above comparing a fixed number and a vector and I had assumed (idiot) that it would have pulled down the vector.
I have tried multiplying the vector and scalar (creating another variable) previous to this function and using this in the if function but still no luck.
I have included a copy of my equation. Your help is greatly appreciated.
Thanks

http://files.engineering.com/getfile.aspx?folder=41077dc2-94a7-4b36-ad43-05

pstuckey (Electrical) · Answer 4 · 2011-09-20 18:18:03

See if the attached is what you're looking for. The two are identical, test1 uses a program, and test2 uses a range variable. The program is more flexible, but some people prefer range variables. If this isn't what you're looking for, please describe the output you are expecting.

Peter

http://files.engineering.com/getfile.aspx?folder=a8e61166-f338-40ee-9bfe-a5

jghrist (Electrical) · Answer 5 · 2011-09-20 23:37:26

When you multiply the vector rein by the scalar Height, you get a vector. When you multiply the two A scalars together, you get a scalar. You can't compare a vector to a scalar.

You could use max(reinadd.n ⋅Heightrein.n) and compare this with max(A1.n ,A2.n). This will compare the highest value of the product (112.25 mm²) with the higher of A1.n and A2.n. Is this what you want?

1clown (Mechanical) · Answer 6 · 2011-09-21 17:32:38

Thanks guys I have got this to work. I used the test 2 option of Peters recomendation and it works a treat as I required a vector output. Thanks also to jghrist for your input.

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If statement using a vector
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