Is there a Continuous Function f:R-->R Discontinuous at All Other Numbers?

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SUMMARY

The discussion centers on the existence of a continuous function f: ℝ → ℝ that is continuous at π and discontinuous at all other numbers. The proposed function f(x) = 0 for irrational x and f(x) = x for rational x was initially considered, but a more suitable function is f(x) = (x - π)¹⁸ for rational x and 0 otherwise. This latter function successfully meets the criteria of continuity at π while being discontinuous at all other points.

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nikolany
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Is there a function f:R-->R that is continuous at π and discontinuous at all other numbers?

Thx

 
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Consider the function f(x)=0 for x irrational and f(x)=x for x rational. Where is that continuous? Can you modify that for your purposes?
 
Dick said:
Consider the function f(x)=0 for x irrational and f(x)=x for x rational. Where is that continuous? Can you modify that for your purposes?

So f(x)=(x-π)^18 for x rational and 0 otherwise should work I think!

Thank you very much
 

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