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VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Mathematical Methods CAS => Topic started by: rhinwarr on November 03, 2013, 08:26:39 am

Title: 'Sign' on TI-nspire
Post by: rhinwarr on November 03, 2013, 08:26:39 am

Does anyone know what 'sign' means. Sometimes I get that in my answer when I'm using my CAS, often when im doing things with absolute values or trig functions.

eg.
dy/dx abs(x) + x^2
=sign(x) + 2x

Title: Re: 'Sign' on TI-nspire
Post by: Manan on November 03, 2013, 09:12:54 am

x (1/Sqrt[x^2] is the Ans
So i guess sign must be "x/Sqrt(x^2)"

Correction: Sign(x) is the function that defines the derivative of modulus of (x) since a modulus can be separated as an hybrid.
Therefore you can look at sign(x) as x/mod

Title: Re: 'Sign' on TI-nspire
Post by: Stevensmay on November 03, 2013, 05:49:14 pm

Quote

Signum is a function that returns whether the number we gave it was positive or negative by outputting 1 or -1 respectively.
Sgn(3) will return 1.
Sgn(-2) will return -1.
Sign(0) will return +-1.

So by including sgn in our answer, we can do away with all the hybrid function stuff as it accounts for whether cos(x) will be positive or negative.