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Find the Fourier transform of generalized functions

${\rm exp}(ix^2)$

My solution: I take the integral for all $\mathbb{R}$

$F({\rm exp}(ix^2))=\frac{1}{\sqrt{2\pi}}\int {\rm exp}(iy^2-ixy)dy=\frac{1}{\sqrt{2\pi}}\int {\rm exp}[(\sqrt{i}y-\frac{ix}{2\sqrt{i}})^2-\frac{ix^2}{4}]dy=$

$\frac{1}{\sqrt{2\pi}}{\rm exp}(\frac{-ix^2}{4})\int {\rm exp}(\sqrt{i}y-\frac{\sqrt{i}x}{2})^2dy=\frac{1}{\sqrt{2\pi}}{\rm exp}(\frac{-ix^2}{4})\int {\rm exp}(-i(\sqrt{i}y-\frac{\sqrt{i}x}{2})i)^2dy$

Then I make a replacement

$u=-i(\sqrt{i}y-\frac{\sqrt{i}x}{2}), du=-i\sqrt{i}dy$

But I do not know in which area to integrate now. Maybe I counted incorrectly

Ralf
  • 35

0 Answers0