Basic math

Divergence:

It is the dot product of nabla operator and a vector field.It gives the degree of Convergence or divergence,Or net flux of the vector field in an infinite decimally small volume of space.

Gradient:

It is the nabla operator of the scalar function.It gives the direction of the steepest ascend at any point of the function.

Curl:

It is the vector product of nabla operator and a vector field.It is another vector field whose direction represents the axis of instantenous rotation of actual vector field and the length represents the magnitude of rotation.

Rank of a matrix

The number of non zero rows in the echolon form of a matrix is called it\'s rank.It represents the maximum number of linearly independent vectors (or equations)of a matrix.