\(t\) 
time 
\(r\) 
Discount rate 
\(V(r)\) 
Present value 
\(C(t)\) 
A cash flow 
\(\delta(t)\) 
A point mass at time 0 
\(a\) 
A rate of growth or decay 
\(\mathcal{L\lbrack}f\rbrack\) 
The LaPlace transform expressed as operator on a distribution \(f\) 
\(F(s)\) 
The LaPlace transform of distribution \(f(t)\) as a distribution in \(s\) 
\(f*g\) 
The convolution of distributions \(f\) and \(g\) 
\(A\) 
The amplitude of a wave 
\(\omega\) 
Wave frequency 
\(\theta\) 
The phase of a wave 
\(s\) 
A complex number 
\(i\) 
\(\sqrt{ 1}\) 
\(\alpha\) 
The real part of a complex number 
\(\overline{s}\) 
The complex conjugate of \(s\) 
\(x\) 
A real number 
\(\widetilde{f}\) 
The Fourier transform of \(f\) 
\(\varphi_{X}\) 
The characteristic function of random variable X 
\(N\) 
The number of observations in a time series 
\(x(n)\) 
An observation of a time series 
\(X(k)\) 
A coefficient of the interpolating series of complex exponentials for \(\omega = 2\pi k/N\) 

