strong_prob4.m

drlt 边界限元程序

%%% Integrate f(x)=x/x+1 on [-2, 2]

clear

eta_strong=[-0.03969687 0.33333333 0.83969687];
weights_strong = [ -2.05166852 1.58823529 0.46343322];
%%% Integrate f(x)=x/x+1
a=-2;
b=2;
xs=-1;
x=xs + (a-xs)*eta_strong;
%finite part integral on [-2, -1]
int_1 = - f_prob4(x)*weights_strong' - f_prob4(xs)*log(abs(xs-a))

x=xs+(b-xs)*eta_strong;
%finite part integral on [-1, 2]
int_2 = f_prob4(x)*weights_strong' + f_prob4(xs)*log(abs(b-xs))

%result
int=int_1 + int_2

x=(a:0.01:b);
y=f_prob4(x);
figure(4)
plot(x,y./(1+x),'Linewidth',2)
title([' Problem 4: f(x)'],'Fontsize',16)
grid on;