Is (-1)^x a discontinuous function?

  • Thread starter Thread starter cp255
  • Start date Start date
AI Thread Summary
The function y=(-1)^x is discontinuous because it oscillates between positive and negative values depending on whether x is an even or odd integer. This creates ambiguity for non-integer values, such as irrational numbers like pi, where the even or odd classification does not apply. The function is only defined for real numbers when abs(x) > 0, leading to undefined values for certain inputs. For example, when x=0.5, the function's output is related to the square root of -1, which is an imaginary number. Thus, the discussion highlights the complexities of defining y=(-1)^x across the real number line.
cp255
Messages
54
Reaction score
0
So I was thinking about the equation y=(-1)x. This equation will jump back and fourth across the x-axis depending on weather x is even or not. This must mean that the function is discontinuous. Figuring out if the value is positive or negative is straight forward for ration numbers but how can we tell if say (-1)^pi is negative or positive since we don't know if pi is even or odd.
 
Mathematics news on Phys.org
It's not that simple. Remember x is a continuous variable, and the quality of even or odd applies only to integers. There are no even or odd rational or irrational numbers.

The equation in the OP is defined for real numbers only when abs(x) > 0. Do you know what y equals when x equals 1/2?
 
Last edited:
I never thought of what it would be be when x=0.5. So I guess it can be positive negative or undefined.
 
Don't you know what it means to raise a number to a power of 0.5? Does square root come to mind?

What is the square root of -1?
 
Insights auto threads is broken atm, so I'm manually creating these for new Insight articles. In Dirac’s Principles of Quantum Mechanics published in 1930 he introduced a “convenient notation” he referred to as a “delta function” which he treated as a continuum analog to the discrete Kronecker delta. The Kronecker delta is simply the indexed components of the identity operator in matrix algebra Source: https://www.physicsforums.com/insights/what-exactly-is-diracs-delta-function/ by...
Suppose ,instead of the usual x,y coordinate system with an I basis vector along the x -axis and a corresponding j basis vector along the y-axis we instead have a different pair of basis vectors ,call them e and f along their respective axes. I have seen that this is an important subject in maths My question is what physical applications does such a model apply to? I am asking here because I have devoted quite a lot of time in the past to understanding convectors and the dual...
Thread 'Imaginary Pythagoras'
I posted this in the Lame Math thread, but it's got me thinking. Is there any validity to this? Or is it really just a mathematical trick? Naively, I see that i2 + plus 12 does equal zero2. But does this have a meaning? I know one can treat the imaginary number line as just another axis like the reals, but does that mean this does represent a triangle in the complex plane with a hypotenuse of length zero? Ibix offered a rendering of the diagram using what I assume is matrix* notation...

Similar threads

Replies
1
Views
2K
Replies
8
Views
5K
Replies
4
Views
5K
Replies
6
Views
2K
Replies
10
Views
2K
Replies
1
Views
2K
Replies
45
Views
5K
Replies
1
Views
1K
Replies
7
Views
1K
Back
Top