What Is Quadrantanopia?

Quadrants are four regions divided by the horizontal and vertical axes in a plane rectangular coordinate system (Cartesian coordinate system). Each region is called a quadrant. It is mainly used in coordinate systems in trigonometry and complex numbers. The quadrant is centered on the origin and the x and y axes are the dividing lines. The upper right is called the first quadrant, the upper left is called the second quadrant, the lower left is called the third quadrant, and the lower right is called the fourth quadrant. The points on the axis do not belong to any quadrant. ^[1]

The quadrant, Quadrant in English, means 1/4 circle equal. Quadrant is

It is said that one day, French philosopher and mathematician Descartes was sick in bed and was very ill. Nevertheless, he repeatedly pondered a question: geometric figures are intuitive, while algebraic equations are relatively abstract. Can geometric figures be combined with algebraic equations, that is, can we use geometric figures to represent equations? To achieve this, the key is how to hook the points that make up the geometry and each set of "numbers" that satisfy the equation. He pondered and worked hard to understand the methods by which "point" and "number" could be linked. Suddenly, he saw a spider on the corner of the roof, and he drew it down with a wire. After a while, the spider climbed up the wire again, and drew left and right over it. Spider's "performance" suddenly made Descartes' thoughts bright.

He thought, you can think of a spider as a point. It can move up, down, left, and right in the house. Can you determine each position of the spider with a set of numbers? He thought again. Adjacent two walls in the house intersect with the ground. If you use the corners on the ground as the starting point and the two lines as the three number axes, the position of any point in the space can be found on these three number axes. Three numbers in sequence. Conversely, you can find a point F corresponding to any set of three ordered numbers in the same space. Similarly, a set of numbers (x, y) can represent a point on the plane, Points can also be represented by a set of two sequential numbers, which is the prototype of the coordinate system.

The creation of the Cartesian coordinate system bridges the gap between algebra and geometry. It allows geometric concepts to be represented by numbers, and geometric figures can also be represented by algebraic forms. Therefore, on the basis of establishing Cartesian coordinate system, Descartes created a branch of mathematics that uses algebraic method to study geometric figuresanalytic geometry.

He boldly conceived that: if the geometric figure is regarded as the trajectory of the moving point, the geometric figure can be regarded as being composed of points with some common characteristics. For example, we can think of a circle as the trajectory of a point with the same distance from a moving point to a fixed point. If we consider the point as the basic element of the geometric figure and the number as the solution of the composition equation, then Algebra and geometry are merged into one. ^[2]