基本函数表达

root中的函数表达和C语言重合，例如:

• sin(x)/x
• [0]*sin(x) + [1]*exp(-[2]*x)
• x + y**2
• x^2 + y^2
• [0]*pow([1],4)
• 2*pi*sqrt(x/y)
• gaus(0)*expo(3) + ypol3(5)*x
• gausn(0)*expo(3) + ypol3(5)*x
• gaus(x, [0..2]) + expo(y, [3..4])

In the last examples above:

• gaus(0) is a substitute for [0]*exp(-0.5*((x-[1])/[2])**2) and (0) means start numbering parameters at 0
• gausn(0) is a substitute for [0]*exp(-0.5*((x-[1])/[2])**2)/(sqrt(2*pi)*[2])) and (0) means start numbering parameters at 0
• expo(3) is a substitute for exp([3]+[4]*x)
• pol3(5) is a substitute for par[5]+par[6]*x+par[7]*x**2+par[8]*x**3 (PolN stands for Polynomial of degree N)
• gaus(x, [0..2]) is a more explicit way of writing gaus(0)
• expo(y, [3..4]) is a substitute for exp([3]+[4]*y)

See below the full list of predefined functions which can be used as shortcuts in TFormula.

TMath 作为表达式的一部分: