I am a noob in Mathematica. I am trying to solve a Quantum Mechanical problem of particle in a one-dimensional box. The program was written for Mathematica 6. But, I ran it in Mathematica 14. The expected output in second to fifth output was like below: Out[45]= 14.0353 Out[46]= 55.7956 Out[47]= 124.253 Out[48]= 217.721 Out[49]= 333.898 But instead, it shows this: Out[45]= -4621.58 Out[46]= -1231.51 Out[47]= -869.209 Out[48]= -504.838 Out[49]= -385.284 See below. What could be causing this? And how to solve the issue?

The equation `Det[A] == 0` is of degree 19 with inexact coefficients. Maybe it is a numerical instability issue. If I try HornerForm[Det[A]] /. Solve[Det[A] == 0] in version 14 I get numbers as high as `-473`. What happens in version 6?

How to run programs written for Mathematica 6 in Mathematica 14? Some programs show a different output than expected in Mathematica 14. For example, look at the attached notebook The program gives this output below the matrix in Mathematica 6: 14.0353 55.7956 124.253 217.721 333.898 14.0642 56.2568 126.578 225.027 351.605 But in Mathematica 14, the ouput below the matrix is: -4621.58 -1231.51 -869.209 -504.838 -385.284 14.0642 56.2568 126.578 225.027 351.605 How can I get the same output as Mathematica 6 in Mathematica 14? What settings should I change? Is there any compatibility setting available? Attachments: 2024-02-21T00_32...nb

Turns out the issue is a version issue. The program shows a different output in Mathematica 14 than in Mathematica 6. How to solve this?

Getting Wrong Numbers in Output for a Quantum Mechanics problem