Equation for spur gear

Can any one tell me the equation for spur gear profile ?

could you send to me an example of spur gear

the equ of spur gear



/*for cartesian coordinate system, enter parametric equation

/*in terms of t (which will vary from 0 to 1) for x, y and z



/*For example: for a circle in x-y plane, centered at origin



/*and radius = 4, the parametric equations will be:



/* x=4*cos (t*360)



/* y=4*sin (t*360)



/* z=0



/*----------------------------------



rb =(PITCH_DIAMETER/2)*cos(PRESSURE_ANGLE)



theta =t*90



theta_rad=(3.1415927/180)*t*90



x=rb*(cos(theta)+ theta_rad*sin(theta))



y=rb*(sin(theta)- theta_rad*cos(theta))