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- Thread starter lonewolf219
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- #1

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- #2

tiny-tim

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… in general, if the function is undefined at a certain point, is that because it does not pass through that specific point?

i don't know what you mean by "pass through" …

functions don't

the function is defined on the subspace consisting of the whole space except that point

- #3

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y=x^2

The graph of this function doesn't "pass through" the point (20,0). Am I correct to say the function y=x^2 is undefined at the point (20, 0) because this point does not lay on the curve of the function? Or would you say the function does not exist at that point...

If I understood what you meant, a function is undefined if it is not continuous at that point (like a cusp, or a jump)?

- #4

tiny-tim

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(try using the X

y=x^2

The graph of this function doesn't "pass through" the point (20,0). Am I correct to say the function y=x^2 is undefined at the point (20, 0) because this point does not lay on the curve of the function? Or would you say the function does not exist at that point. …

ah, i see what you mean

no, the function y = x

y is defined at all values of x, not of (x,y)

(eg y is defined at 0,and the graph goes through (0,0))

if a function z is undefined at (0,0), that means the graph (a surface) has a hole in above the origin

- #5

HallsofIvy

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Similarly, [itex]f(x,y)= 1/(x^2+ y^2)[/itex] is a function that maps (x, y), a point in R

- #6

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I hope I know what you guys know one day...

you guys are brilliant!

you guys are brilliant!

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