8 Replies Latest reply: Nov 29, 2012 6:51 PM by YB24
Level 1 (0 points)

Here are two graphs

1

2

MacBook Air
• ###### 1. Re: Is there something wrong with my Grapher？
Level 1 (0 points)

My question is,these two equations are the same,right?

But why the first equation only show x on positive x axis?

Did I do something wrong?

• ###### 2. Re: Is there something wrong with my Grapher？
Level 10 (118,270 points)

The functions are not the same. In the first case, you're raising a real number to a fractional power. That's ambiguous for negative arguments, so the program only graphs it for non-negative arguments. In the second case, you're raising a non-negative number to a fractional power.

• ###### 3. Re: Is there something wrong with my Grapher？
Level 1 (0 points)

Why this?

• ###### 4. Re: Is there something wrong with my Grapher？
Level 10 (118,270 points)

I agree, that's inconsistent.

• ###### 5. Re: Is there something wrong with my Grapher？
Level 1 (0 points)

And more examples

Is this a big bug in Grapher?I will keep this post updated.

Here are some polynomial examples.

Anothe set

• ###### 6. Re: Is there something wrong with my Grapher？
Level 1 (0 points)

And more examples

• ###### 7. Re: Is there something wrong with my Grapher？
Level 1 (0 points)

And change 3 to 5

It seems that Grapher only shows function on whole domain when exponent is integer.

• ###### 8. Re: Is there something wrong with my Grapher？
Level 2 (200 points)

Hi AveMaleficum !

It is NOT inconsistent at all Mr. Linc Davis : just go back to the mathematical definitions !

Generally, by definition, rational exponents  p = m / n can be applied only to a positive number as says :

http://www.edu.upmc.fr/physique/lp326/dossiers/math-chap5.pdf  (French but easy to translate) or Wikipedia :

« Limits of rational exponents

Since any irrational number can be approximated by a rational number, exponentiation of a positive real number b with an arbitrary real exponent x can be defined by continuity with the rule… »

Same rule for real exponents : try  y = x^π  for example.

But  if  p is an integer  a^p  a > or < 0, if  p = 1 / n with n an odd integer, a^(1/n), a may be < 0.