[Solved] What is the: Correct way for subtraction in Fortran

Question

You are simply mis-reading your output. You claim that the output is:

-4.59045

That claim is contradicted by the screenshot. The actual output is:

-4.5904569E-10

That is a very small number, very close to zero. Note also that your actual value is specified to 10 significant digits, commensurate with the relative error that your program reports. In other words it seems that your estimate is accurate and that your program is behaving correctly.

Accepted Answer

You are simply mis-reading your output. You claim that the output is:

-4.59045

That claim is contradicted by the screenshot. The actual output is:

-4.5904569E-10

That is a very small number, very close to zero. Note also that your actual value is specified to 10 significant digits, commensurate with the relative error that your program reports. In other words it seems that your estimate is accurate and that your program is behaving correctly.