Create empty vector/matrix x |
x = [] |
x = c(); x = data.frame() |
Add a new column/row v to x |
x = [x, v]; x = [x; v] |
x = cbind(x, v); x = rbind(x, v) |
Transpose a matrix x |
x = x.' |
x = t(x) |
| Number of rows of a matrix |
size(x, 1) |
nrow(x) |
| Number of columns of a matrix |
size(x,2) |
ncol(x) |
Elementwise multiplication/division of vectors v1 and v2 |
v1 .* v2; v1 ./ v2 |
v1 * v2; v1 / v2 |
Delete the first/last column of x |
x(:,1) = []; x(:,end) = [] |
x = x[,-1]; x = x[,-ncol(x)] |
Delete the last two rows of x |
x((end-1):end,:) = [] |
x = x[-c(nrow(x)-1,nrow(x)),] |
Create a scatter plot of vector pairs (x,y) |
scatter(x,y) |
plot(x,y) |
| For loop |
for i=1:10 … end |
for(i in 1:10){...} |
| If, else if |
if x==1 … else if x < 2 … end |
if(x == 1){...} else if(x<2){...} |
| Logic (0/1) vector indicating elements in a vector is larger than 1 |
logic = (x>1) |
logic = (x>1) |
| Index of elements that satisfies a condition |
ind = find(x>1) |
ind = which(x>1) |
| Retrieve elements that satisfies a condition |
x(x>1); x(find(x>1)) |
x[x>1]; x[which(x>1)] |
| Solve $x$ from $Ax = B$ |
x = A\B |
x = Solve(A, B) |
| Identity matrix of dimension $n$ |
eye(n) / eye(n,n) |
diag(n) |
| Eigen value and eigen vectors of matrix $x$ |
[vectors, values] = eigs(x) |
ev = eigen(x); ev$values; ev$vectors |