Conversion table between IT++ syntax and Matlab/Octave

Here we provide a conversion table between Matlab/Octave and IT++ syntax. This table is intended to help with the transition from Matlab/Octave programming to IT++, but it is not an exhaustive list of possible operations.

In what follows,

• a, b denote vectors (assumed to be column vectors in Matlab/Octave notation),
• A, B denote matrices,
• x is a scalar,
• k, l, n are indices

Vector indexing and manipulation:

a.length()                           // length(a)
a(0)                                 // a(1)
a(1)                                 // a(2)
a(k-1)                               // a(k)
a(k-1)=x;  or a.set(k-1,x);          // a(k)=x;
a.left(k)                            // a(1:k)
a.right(k)                           // a(end-k+1:end)
a.mid(k,l)                           // a(k:k+l-1)
a.del(k);                            // a=[a(1:k-1); a(k+1:end)];
concat(a,b)                          // [a; b] (or [a.' b.'].')
a.clear();                           // a=zeros(size(a));  (or a=complex(zeros(size(a)));)
to_cmat(a)                           // complex(a)   (assuming a real-valued)

Note that indexing in IT++ starts at 0, whereas indexing in Matlab starts at 1. Also note that Matlab/Octave does distinguish between column and row vectors, whereas IT++ does not.

Matrix indexing and manipulation:

A.rows()                             // size(A,1)
A.cols()                             // size(A,2)
A(k-1,l-1)                           // A(k,l)
A.set(k-1,l-1,x)                     // A(k,l)=x
A.get_col(k-1)                       // A(:,k)
A.get_row(k-1)                       // A(k,:)
A.set_col(k-1,a)                     // A(:,k)=a
A.set_row(k-1,a)                     // A(k,:)=a
A.append_row(a)                      // A=[A; a.']
A.append_col(a)                      // A=[A a]
A.transpose()                        // A.'
A.hermitian_transpose()              // A'
A.clear()                            // A=zeros(size(A))  [or A=complex(zeros(size(A)))]
to_cmat(A)                           // complex(A)   (assuming a real-valued)

Some vector and matrix algebra:

a+b                                  // a+b
a-b                                  // a-b
elem_mult(a,b)                       // a.*b  (elementwise product)
a*b                                  // a.'*b (inner product)
conj(a)*b                            // a'*b (inner product)
outer_product(a,b)                   // a*b.' (outer product)
elem_div(a,b)                        // a./b
A+B                                  // A+B
A-B                                  // A-B
A*B                                  // A*B
elem_mul(A,B)                        // A.*B
elem_div(A,B)                        // A./B
ls_solve_od(A,b)                     // A\b    (assuming the system is overdetermined)

Special matrices and vectors:

zeros(n,n)                           // zeros(n,n)
zeros_c(n,n)                         // complex(zeros(n,n))
eye(n)                               // eye(n)
eye_c(n)                             // complex(eye(n))
linspace(alpha,beta,n)               // linspace(alpha,beta,n)

Hardcoded initializations:

mat X="1.1 1.2; 2.1; 2.2";           // X=[1.1 1.2; 2.1 2.2];
ivec a="1 2 3 4 5";                  // a=[1; 2; 3; 4; 5]; (or a=[1 2 3 4 5].';)
ivec a="1:-3:-8";                    // a=1:-3:-8;