20251117

lab1/exercise1.m

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+% 练习1
+x=linspace(-pi,pi,21)
+y=sin(x)
+% 练习2
+clear
+k=1:1000;
+kk=1./k;
+kkk=kk./k;
+res=sum(kkk)-(pi^2)/6
+% 练习3
+sum(kk-log(1000))
+% 练习4
+clear
+a=rand(2,3)
+x=a(1,:)
+y=a(2,:)
+norm(x)
+norm(y)
+acos(dot(x,y)/norm(x)/norm(y))
+% 练习5
+clear
+rand(3)
+det(ans)  % 线性无关
+% 练习6
+clear
+a=rand(3,2)
+x=a(1,:)
+y=a(2,:)
+z=a(3,:)
+alpha=x-z
+beta=y-z
+alpha=[alpha 0]
+beta=[beta 0]
+cross(alpha,beta)
+% 练习7
+clear
+a=11:19
+b=a
+for k=1:8
+    b=[b;a+10*k];
+end
+rank(b)
+% 练习8
+y=[]
+for x=-6:0.05:6
+    y=[y difun(x)];
+end
+plot(x,y)
+plot([-6:0.05:6],y)
+% 练习9
+A=[6,2,1,-1;2,4,1,0;1,1,4,-1;-1,0,-1,3];
+b=[6;1;5;-5]
+x=A\b
+% 练习10
+[diag(1:4) eye(4)]
+% 练习11
+num2p(123453656345)
+% 练习12
+ttry(100)