Thank you for your reply.

It's an honor for me that a very qualified and intelligent person like you, replied to my question.

I apologize but not really understood your answer.

I read carefully the manual, and then updated the post, so the question in the top is after reading the manual.

I run this code on Microsoft Visual Studio:
Code
        double a1 = 0.56434;
        double a2 = 0.56506;
        printf("\n %.10e %.10e %.10e", a1, a2, (a1 - a2) / a2);


Please see the attached VC results

I run this code on Phyton:
Code
a1 = 5.6434e-1
a2 = 5.6506e-1

print("\n {:.10e} {:.10e} {:.10e}".format(a1, a2, (a1 - a2) / a2))


Please see the attached Python results.

I run this calculation on RStudio and got the attached file.

I run this calculation on PC's calculator and got the attached file.

I don't understand why coding with 4 different languages/application provide the same results, but Zorro result differs?

Thanks
David

Attached Files Screenshot (4).pngScreenshot (3).pngScreenshot (5).pngScreenshot (1).png