C++ :: Parabolic Shot Program - Calculate And Graph Time Vs Distance

It is supposed to calculate and graph time vs. distance. The problem I have is graphing, if I put too small values for Vi, which is the initial velocity, it just graphs one or two points, because t is too small. I already tried to adjust t with 'if(t<10) t=t*10; if (t>100) t=t/10;', But it seems not to solve my problem.

Other truble I have is that, as the graph is parabola, core values ​​are very close together, and when plotted, these values ​​are in the same line on the screen.

Here is my code:
#include<stdio.h>
#include<conio.h>
#include<math.h>
void main() {
float x, y, hmax, t, amax, vi, v, a, b, g, ang; /*x= x coordinate, y= y coordinate, hmax= maximum height,

[Code] .....