How to create a graph of sine in qbasic

Sine is the trigonometrical function based on right angled triangle .  when we plot the value of sine in graph paper you will get the result as below . It is very easy to plot sine in graph paper .Taking a calculator and a graph paper is enough for that job . 


Now lets learn how to create the sine wave in the computer using qbasic . It is preety easy to create a sine wave in qbasic so lets get started

< Step 1 /> : create a loop

create a loop starting from 0 to 360 and define screen as we are playing with graphics . 

cls

screen 13

for i = o to 360

next i

< Step 2 /> : convert the numbers into radians and use the SIN function.

you have to convert numbers into radians as SIN function requires the angle argument to be in radians. the formula is :

                                              (x/180)*pie 

where x is angle and value of pie = 3.1415

so we can write like this :

cls

screen 13

for i = o to 360

x= sin((i/180)*3.1415)

next i

<Step 3/> : using pset function to draw it on screen.

the last thing is you use pset function to get it drawn on screen and it goes like this.

cls

screen 13

for i = o to 360

x= sin((i/180)*3.1415)

pset(i,(x*50)+50),4

next i

ok now lets look at pset . while using pset function x is multiplied and added with 50 . it is the way of defining the amplitude. if you set it to zero then you would just get a straight line so you have to define the amplitude.while using pset instead of i you can use (i/360)*320 because we used screen 13 and it is just 320 pixels whereas sine wave is 360 pixels .  

here is the final program :

cls

screen 13

for i = o to 360

x= sin((i/180)*3.1415)

pset((i/360)*320,(x*50)+50),4

next i