Let f(x)=(−∞,∞){\displaystyle f(x)=(-\infty ,\infty )} and
suppose
Then we have the functions below.
This function f(t){\displaystyle f(t)} is referred to as Fourier integral.
This function f^(ω){\displaystyle {\hat {f}}(\omega )} is referred to as fourier transform as we previously learned.