diary lesson1.txt

a=zeros(1000,1000);
size(a)

realmax

ans =

  1.7977e+308

realmin

ans =

  2.2251e-308

a=1

a+0.001

a+0.000001

format long
a+0.000001

a+0.0000000001

a+0.00000000000001

a+0.00000000000001

b=a+0.00000000000001

b-a

b=a+0.00000000000000000001 % fa 1

b-a % fa 0

% Numero macchina
eps %    2.220446049250313e-016

1+eps

whos a % sprecone

  b=zeros(1000,1000,'single');
whos b

c=zeros(1000,1000,'uint8');
whos c

a=1:10


a=1:0.1:10

a=linspace(1,10,10)

b=linspace(1,10,15)

a(3)

a(3:6)

a(12)

size(a)

a(15)=55;
size(a)

a

a(5)=[];
a

size(a)

m=rand(6,3)

m(4,2)=[]; % Errore

m(4,:)=[];
m

size(m)

m(:,1:2)=[];
m

m=rand(4,7);
m

m2=[m(:,1:5) [1;2;3;5] m(:,6:7) ];
size(m2)

m2


p=[1 2 3 4 5
6 7 8 9 10
]

a=randn(1000,1);
mean(a)

std(a)

figure(1)
hist(a)

a(a>1.5)=1.5;

hist(a)
a(a<-1.5)=-1.5;
hist(a)

a(a<0.5 & a>-0.5)=0;
hist(a)
hist(a,20)
a(a<-1 | a>1)=3;
hist(a,20)

a=randn(1000,3);
hist(a)
at=a';

size(at)
hist(a)
hist(at)

hist(at')

a=magic(15);

a

sum(a)

sum(a')

sum(diag(a))


q=a(a>100);
q

length(q)

a=rand(10,1);
b=rand(10,1);

for i=1:10
c(i)=a(i)+b(i)
end


edit prova1
N=100;
a=rand(N,1);
b=randn(N,1);
tic
for i=1:N
    c(i)=a(i)+b(i);
end
toc
prova1

% Lento
clear all

N=10000;
a=rand(N,1);
b=randn(N,1);
tic
for i=1:N
    c(i)=a(i)+b(i);
end

% Veloce (c gia' definito)
N=10000;
a=rand(N,1);
b=randn(N,1);
tic
for i=1:N
    c(i)=a(i)+b(i);
end
toc

%  Di nuovo lento
clear all

N=10000;
a=rand(N,1);
b=randn(N,1);
tic
for i=1:N
    c(i)=a(i)+b(i);
end
toc


clear all
% Veloce (c definito)
N=10000;
a=rand(N,1);
b=randn(N,1);
c=zeros(N,1);
tic
for i=1:N
    c(i)=a(i)+b(i);
end
toc

% Vettoriale
clear c
tic
c=a+b;
toc



a='Prima stringa';
a

a='L'articolo' % Errore

a='L''articolo'

a='Prima stringa';
b=[a '-Seconda stringa']


whos b

a=['Stringa1']

a=[a; 'Stringa2']

a=[a; 'Stringa3']


a=[a; 'Stringa9']

a=[a; 'Stringa10'] % Errore
size(a)

cc=cell(11,1);
cc


cc{1}='Stringa 1'

cc{2}='Stringa127';
cc

cc{3}=-48;

cc{4}=ones(100,100);
cc

diary off