matlab讲义5.ppt

1、Week 5,Relation and logical operators Controlling statements: for, while and if Generating Poisson Distribution,Relational and Logical Operators,Relational operators available , =, =, = Logical operators to combine relational expressions: % sum a random vector s = 0; for i = 1:100 s = s+a(i); end %

2、this can also be done by sum(a);,Example: for,% sum only the odd-index entries a = rand(100); s = 0; for i = 1:2:100 s = s+a(i); end,Example: for,A = zeros(k,k) % Hilbert matrix for m = 1:k for n = 1:k A(m,n) = 1/(m+n -1); end end,Example: for,% Matrix multiplication C = A*B for m = 1:k for n = 1:k

3、for j = 1:k C(m,n) = C(m,n) + A(m,j)*B(j,n); end end end,Example: for,while construct while . end if construct if else (elseif ) () end,a = rand(1,100); % sum a random vector s = 0; j=1; while j 101 s = s+a(j); j = j+1; end,Example: while,if A B disp(A is larger) elseif A B disp(B is larger) elseif

4、A = = B disp(A equals B) else disp(Unexpected situation) end,Example: if,for j=1:class_size if score(j) = 90 grade(j)=A; elseif score(j) = 80 grade(j)=B; else grade(j)=F; end end,Example: if,Generating Poisson Distribution,Set k=0 and P=1 Generate a uniformly distributed random number Uk+1 and replace P by P*Uk+1 If accept X = k, else k increases by one and return to Step 2,for i=1:N, k=0;p=1; u=rand; p=p*u; while p=exp(-lambda) u=