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Is Wronskian sign arbitrary?

by 1MileCrash
Tags: arbitrary, sign, wronskian
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Mar20-13, 06:38 PM
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On my DE test, I was asked to determine if two solutions to a DE are fundamental solutions.

So I confirmed they were both solutions, and took the Wronskian, which was nonzero.

I got points marked off, and he put a minus sign in front of my wronskian result.

Isn't the sign of the Wronskian determined by what function I call y1 and what function I call y2 and is thus completely arbitrary?
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Mar20-13, 10:36 PM
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Yes the sign on the Wronskian is determined by the ordering that you assign to the functions. It's a weak excuse, but the grader was probably just comparing your answer with their solution sheet and saw the sign difference and didn't think about why they were different.
Mar25-13, 09:38 AM
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Well, I looked at the test and on the paper the functions were called y1 and y2 already, and in my work I did write W[y1,y2] = my wronskian.

So I guess I can understand. I don't think I'll argue this one. I noticed that the wronskian order is arbitrary early off and have just been taking the easier derivative first.

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