How will be the idea of Brahmagupta (598 -668 ?) ?:
Confusions as in the attached:
The division by zero has a long and mysterious story over the world (see, for example, H. G. Romig \cite{romig} ) with its physical viewpoints since the document of zero in India on AD 628. In particular, note that Brahmagupta (598 -668 ?) established the four arithmetic operations by {\bf introducing $0$ and at the same time he defined as $0/0=0$} in Brāhmasphuṭasiddhānta. Our world history, however, stated that his definition $0/0=0$ is wrong over 1300 years. We will see that his definition is right and suitable. Indeed, we will show typical examples: The conditional probability $P(A|B)$ for the probability of $A$ under the condition that $B$ happens is given by the formula $$ P(A|B) = \frac{P(A \cap B)}{P(B)}. $$ If $P(B) = 0$, then, of course, $P(A \cap B) =0$ and $P(A|B) = 0$ and so, $0/0=0$. For the differential equation $$ \frac{dy}{dx} = \frac{2y}{x}, $$ we have the general solution with constant $C$ $$ y = Cx^2. $$ At the origin $(0,0)$ we have $$ y^{\prime}(0) = \frac{0}{0} =0. $$ For three points $a,b,c$ on a circle with center at the origin on the complex $z$-plane with radius $R$, we have $$ |a + b + c| = \frac{|ab + bc + ca|}{R}. $$ If $R =0$, then $a,b,c =0$ and we have $0=0/0$. For the second curvature \begin{equation} K_2 = \left((x ^{\prime \prime})^2 + (y^{\prime \prime})^2 + (z^{\prime \prime})^2 \right)^{- 1}\cdot \begin{vmatrix} x^\prime & y^\prime & z^\prime\\ x ^{\prime \prime}& y^{\prime \prime}& z^{\prime \prime}\\ x^{\prime \prime \prime} & y{\prime \prime \prime}& z{\prime \prime \prime} \end{vmatrix}, \end{equation} if $ (x ^{\prime \prime})^2 + (y^{\prime \prime})^2 + (z^{\prime \prime})^2 =0$; that is, when for the case of lines, then $0 = 0/0$. For the function sign $x$ $= x/|x|$, we have, {\bf automatically}, sign $x = 0$ at $x=0$. We have many and many concrete examples. The division by zero is uniquely and reasonably determined as 1/0=0/0=z/0=0 in the natural extensions of fractions. We have to change our basic ideas for our space and world Division by Zero z/0 = 0 in Euclidean Spaces Hiroshi Michiwaki, Hiroshi Okumura and Saburou Saitoh International Journal of Mathematics and Computation Vol. 28(2017); Issue 1, 2017), 1 -16. http://www.scirp.org/journal/alamt http://dx.doi.org/10.4236/alamt.2016.62007 http://www.ijapm.org/show-63-504-1.html http://www.diogenes.bg/ijam/contents/2014-27-2/9/9.pdf http://okmr.yamatoblog.net/…/announcement%20326-%20the%20di… http://okmr.yamatoblog.net/ Relations of 0 and infinity Hiroshi Okumura, Saburou Saitoh and Tsutomu Matsuura: http://www.e-jikei.org/…/Camera%20ready%20manuscript_JTSS_A…