i dont understand most of it but there is something i remember...I was looking at the 3D plane in calculus with the 3 coordinates (x,y,z) and i remember seeing this in my calculus book...

I remember seeing that the y is the vertical axis, the x i think is the horizontal axis and z is the axis of DEPTH...Now i am looking at the calculus book and it shows Z as the vertical plane (as y-axis)...I dont know if someone had been playing with it...But i do remember seeing Z as the axis of depth before in my calculus book before years ago....

Even if i am wrong WHY did they change it now, doesnt that causes confusion...It is just proving what i have been saying...

not that i would had understood my calculus book but still...

we all have been accustomed to the Y axis as been the vertical axis, the axis of height...