asked on # Math Stumper

EE Pros (and Math Wizards),

I have a program that calculates the difference between a "BEFORE" and an "AFTER" number and represents it as a % Change. It works great when both numbers are positive. BUT.... if the BEFORE value is negative and the AFTER value is positive, it does not calculate the result correctly. Either my formula is wrong or I'm dealing with an anomaly in math......... ;-(

See Attached WS/file.

Thank you in advance!

B.

Measuring-a-Change.xls

I have a program that calculates the difference between a "BEFORE" and an "AFTER" number and represents it as a % Change. It works great when both numbers are positive. BUT.... if the BEFORE value is negative and the AFTER value is positive, it does not calculate the result correctly. Either my formula is wrong or I'm dealing with an anomaly in math......... ;-(

See Attached WS/file.

Thank you in advance!

B.

Measuring-a-Change.xls

Math / Science

-1 to +2 is a change of -300%

The -1 represents 100% of the original value.

A change of +3 is -3*-1 or 300% of the original value.

The -1 represents 100% of the original value.

A change of +3 is -3*-1 or 300% of the original value.

Log in or sign up to see answer

Become an EE member today7-DAY FREE TRIAL

Members can start a 7-Day Free trial then enjoy unlimited access to the platform

or

Learn why we charge membership fees

We get it - no one likes a content blocker. Take one extra minute and find out why we block content.

Not exactly the question you had in mind?

Sign up for an EE membership and get your own personalized solution. With an EE membership, you can ask unlimited troubleshooting, research, or opinion questions.

ask a question
Thanks ShannonEE and d-glitch for jumping in here.

Here's my problem. The math may be correct, but it flies in the face of logic. When I have a negative number and turn it positive, logically "it's an improvement". So the growth, or change should be positive. But mathematically, it's not.

Say for example, the CURRENT number represents a loss of -3% and the FUTURE is a gain of +2%. That's a difference of +5%. Is there a way to solve for the difference between the math and the logic in situations where you start with a negative number and move into a positive direction to produce a positive improvement to the change?

Is this logic vs. math? I'm surprised there is a difference..........

B.

Here's my problem. The math may be correct, but it flies in the face of logic. When I have a negative number and turn it positive, logically "it's an improvement". So the growth, or change should be positive. But mathematically, it's not.

Say for example, the CURRENT number represents a loss of -3% and the FUTURE is a gain of +2%. That's a difference of +5%. Is there a way to solve for the difference between the math and the logic in situations where you start with a negative number and move into a positive direction to produce a positive improvement to the change?

Is this logic vs. math? I'm surprised there is a difference..........

B.

All of life is about relationships, and EE has made a viirtual community a real community. It lifts everyone's boat

William Peck

Get an unlimited membership to EE for less than $4 a week.

Unlimited question asking, solutions, articles and more.

Alexandre, I used your formula. You nailed what I was trying to do in addition to answering the question from a math perspective. ShannonEE, thanks also for your commentary to help me better understand the situation.

You will get odd looking results when the

beforeandafterchange sign.