实验1.1

吉林大学 计算方法实验课 实验1.1

代码用octave语言编写。

实验题目:

实验1.1_第1张图片

实验代码:

function [x,y,l,u] = zhuigan(n)

%初始化ax=b
a = zeros(1,n-1);
for i = 1:n-1
  a(i) = 1;
  end

b = zeros(1,n);
for i = 1:n
  b(i) = -4;
  end
  
c = a;

d = zeros(1,n);
d(1) = -27;
for i = 2:n
  d(i) = -15;
  end

%将a设置为n维向量

if length(a)==(n-1)

   for i = n-1:-1:1

       a(i+1)=a(i);

   end

end              

%  LU 分解

u = b; l = b;

for i = 2:n

   l(i) = a(i)/u(i-1);  u(i) = b(i) - l(i) *c(i-1);

end

%  Ly = d

y = d;

for i = 2:n

   y(i) = d(i)-l(i)*y(i-1);

end

%  Ux = y

x = y; x(n) = y(n)/u(n);

for i = n-1:-1:1

   x(i) = (y(i)-c(i)*x(i+1))/u(i);

end
disp(x);
endfunction

实验现象:

(1)n = 10

实验1.1_第2张图片

(2)n=100

实验1.1_第3张图片

实验1.1_第4张图片

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