What is Continuity of Function and How Does it Lead to A+B=C?

In summary, the discussion in the linked post describes the continuity of a function and its derivative at a given point, which leads to a specific relationship between the parameters A, B, and C in the function. This understanding is crucial in solving the simple-step scattering problem for E<V.
  • #1
nathangrand
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In this post: https://www.physicsforums.com/showthread.php?t=230996

..continuity of the function is described. I don't understand what this means but know that it leads to A+B=C

Can someone offer an explanation as to what continuity is and why it leads to this
 
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  • #2
nathangrand said:
In this post: https://www.physicsforums.com/showthread.php?t=230996

..continuity of the function is described. I don't understand what this means but know that it leads to A+B=C

Can someone offer an explanation as to what continuity is and why it leads to this
Here is a part of what was posted in the link to which you refer:
analyzing the simple-step scattering problem for E<V, we find that the solution to the schroedinger equation is:

PHI(left) = Aexp(ikx)+Bexp(-ikx)
PHI(right) = Cexp(-qx)

Continuity of the function and it's derivative at x=0 gives the relations between the parameters A, B and C.

The function, Φ(x), is continuous at x=0 provided that:
lim(x→0)Φ(x) = Φ(0) = lim(x→0+)Φ(x).​
This gives A + B = C = Φ(0)
The derivative is continuous if a similar relationship holds for it.

This gives: A ‒ B = -qC/(ik)
 
  • #3
Thanks I get it now!
 

What is continuity of function?

Continuity of function is a property of mathematical functions that describes the smoothness and connectedness of the graph. It means that there are no breaks or jumps in the graph and that the function can be drawn without lifting the pen from the paper.

How is continuity of function determined?

Continuity of function is determined by three criteria: the function is defined at the point in question, the limit of the function exists at that point, and the limit equals the value of the function at that point. If all three criteria are met, the function is considered continuous at that point.

What is the difference between continuity and differentiability?

Continuity and differentiability are related but distinct properties of functions. Continuity means that there are no breaks or jumps in the graph, while differentiability means that the function has a well-defined derivative at that point. A function can be continuous but not differentiable, but if a function is differentiable, it must also be continuous.

How does continuity of function affect the behavior of a function?

Continuity of function is important in understanding the behavior of a function. If a function is continuous, it means that small changes in the input result in small changes in the output. This allows us to make predictions and analyze the behavior of a function with more accuracy.

Why is continuity of function important in real-world applications?

Continuity of function is important in real-world applications because it allows us to model and analyze real-world phenomena with mathematical functions. These functions can then be used to make predictions, optimize processes, and solve problems in various fields such as physics, engineering, economics, and more.

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