Julia語言 例題4-3 梯形法求標準常態分配的面積

Julia語言 例題4-3 梯形法求標準常態分配的面積

 



a=-5  , b=5 , n=100

#================================================
 * ex4-3.jl based on Trapezoidol Rule is
 * used for computing definite integral with
 * domain [a,b] with n even-grids.
 *
   梯形法 T'= (h/2) [ f(a) + f(b) + 2 sigma i=1 to n-1 f(xi)]

=================================================#

using Printf

function f(x::Float64) #// 欲微分函數
    return (1.0/exp(x*x/2))
end

result=0.0
n=100
a=-5.0
b=5.0

h=(b-a)/n
x=a
for i=1:n
    x=x+h;
    result=result+f(abs(x))
end

tn=(1.0/sqrt(2* pi ))*(h/2.0)*(f(abs(a))+f(abs(b))+2.0*result)

s=@sprintf("T%d=%10.6lf\n",n,tn)
println(s)

輸出畫面

T100=  1.000000