# Disable negative r in polar coordinates

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### #1 lordg2202

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Posted 20 February 2020 - 11:46 AM

Is it possible to disable negative r in polar graphs? E.g. make r=sin(4x) have only 4 petals instead of 8? The exam I'm sitting has this convention, and I want to be able to make use of this feature. Using cg50 for reference. The tutorial provided by casio is very workaround and basically only works when there is one interval of r that is negative(on their youtube channel) which works by finding the highest value of theta where r>0 then adjusting the domain. This obviously wont work in my example as there would be multiple intervals needed.

### #2 lordg2202

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Posted 21 February 2020 - 06:15 PM

If anyone is wondering how to work around this in the future, what I have done is say I have r=sin(4x), change this to (sqrt(sin4x) + 0.0000001)^2.  Unfortunately without adding the 0.0000..1, the expression is automatically simplified or something like that, so you will still get negative rs including when absolute value is used(Interesting design choice!). Any graph features will obviously be useless but is alright for sketches.

### #3 Tritonio

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Posted 11 March 2020 - 08:32 PM

What? That's a big bug if it simplifies sqr(x^2) to x and not to abs(x).

### #4 lordg2202

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Posted 26 April 2020 - 10:32 AM

What? That's a big bug if it simplifies sqr(x^2) to x and not to abs(x).

abs(x) does not work at all in polar. You can type it in but it doesnt do anything.

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