Why is this C expression yielding the wrong answer? [closed]

Question

This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, visit the help center.

Closed 8 years ago.

I have the following code:

double e = 36858.767828375385;
double c = 2;
double d = 67.877433500000009;

e = sqrt(e / (c * (c - 1))) / d;

The resulting value of e is 2, according to the debugger, but it should be 2.8284271. What am I doing wrong?

Answer 1

The reason e takes the value 2 is because that's the actual answer:

sqrt(e / (c * (c-1))) / d;

= sqrt(e / (2 * (2 - 1))) / d

= sqrt(e / 2) / d

= sqrt(36858.767828375385 / 2) / d

= sqrt(18429.383914188) / d

= 135.754867 / d

= 135.754867 / 67.877433500000009

= 2

Perhaps you have the wrong formula?

Hope this helps!

Answer 2

Sample code:

c = 2;
c = c * (c - 1);

Evaluation will be 2 * (2 - 1) => 2 CORRECT (Actual result of 2);

It will not be 1 * (2 - 1) => 1 WRONG (your expectation of 2.8284271);

This is what your confusion, I guess.