How to get the negative out of my calculation

Question

0.00/5 (No votes)

See more:

I have three textboxes that do calculations on a textbox text change. When the calculations is done there is a negative in the answer. Here is my code:

C#

int k = Convert.ToInt32(TextBox1.Text);
int l = Convert.ToInt32(TextBox2.Text.Replace(",", ""));
TextBox3.Text = Convert.ToString((k - l) * 100.0 / ((k + l) / 2));
TextBox3.Text = Math.Round(Convert.ToDouble(TextBox3.Text), 2).ToString();

Here is what I am trying to do.

HTML

Calculate percentage difference
between V1 = 100 and V2 = 1000

( | V1 - V2 | / ((V1 + V2)/2) ) * 100

= ( | 100 - 1000 | / ((100 + 1000)/2) ) * 100
= ( | -900 | / (1100/2) ) * 100
= ( 900 / 550 ) * 100
= 1.636364 * 100

= 163.6364% difference 

It is from this website:

<a href="http://www.calculatorsoup.com/calculators/algebra/percent-difference-calculator.php">http://www.calculatorsoup.com/calculators/algebra/percent-difference-calculator.php</a>[<a href="http://www.calculatorsoup.com/calculators/algebra/percent-difference-calculator.php" target="_blank" title="New Window">^</a>]

How will I get the negative out?

Posted 20-Oct-14 16:18pm

Computer Wiz99

Add a Solution

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

User 59241 · Accepted Answer · 2014-10-20T16:32:00

Solution 1

When you see the formula:
Percent difference = ( | ΔV |/ ( ∑V/2) ) * 100 = ( | (V1 - V2) | / ((V1 + V2)/2) ) * 100

You know you must use the absolute value (http://en.wikipedia.org/wiki/Absolute_value[^]) of the difference V1-V2 thus:

TextBox3.Text = Convert.ToString((Math.Abs(k - l)) * 100.0 / ((k + l) / 2));

This will make the difference always non-negative.

To round:

TextBox3.Text = Convert.ToString(Math.Round((Math.Abs(k - l)) * 100.0 / ((k + l) / 2)));

Posted 20-Oct-14 16:32pm

User 59241

Updated 20-Oct-14 16:49pm

v3

Comments

Computer Wiz99 20-Oct-14 22:39pm

pwasser, Thanks for the code. I have one more question. How do I round to the whole number to get rid of the decimal and the numbers after that?

[no name] 20-Oct-14 22:49pm

Have edited.

Computer Wiz99 20-Oct-14 23:05pm

I already do rounding. Look at my code for the rounding.