实验一答案

1. (1) z1=2*sin(85/(2*pi))/(1+exp(2));

(2) x=[2 1+2*i;-.45 5]; z2=1/2*log(x+sqrt(1+x.^2))

(3) a=-3:.1:3; z3=.5*(exp(.3*a)-exp(-.3*a))+log((.3+a)/2) (4) t=0:.5:2.5;

z1=t.^2; z2=t.^2-1; z3=t.^2-2*t+1;

z=[(t>=0&t<1).*z1; (t>=1&t<2).*z2;(t>=2&t<3).*z3 ]; k=find(z~=0); l=find(z==0); n=z(k);

z4=[0 n(1:l(2)-1)’ 0 n(l(2)-1:end)] plot(t,z4);

2 A=[12 34 -4;34 7 87;3 65 7]; B=[1 3 -1;2 0 3;3 -2 7]; (1) A+6*B; A-B+eye(size(A)); (2) A*B; A.*B

(3) A^3; A.^3; (4) A/B B\\A

(5) [A, B]; [A([1,3],:); B^2]

3. a=1:25; A=reshape(a,5,5)’; B=[3 0 16;17 -6 9;0 23 -4;9 7 0;4 13 11]; (1) C=A*B; (2) D=C(3:end,1:2)

4. (1) x=100:999; A=rem(x,21); B=find(A==0); length(B) (2) ch=’Abdfedrer’; k=find(ch>=’A’&ch<=’Z’); ch(k)=[];