Question for SunnyCoder

Posted on 2004-04-24
Last Modified: 2010-08-05
Hey man. I wanted to write a program to process simple algebra problems..


3x + 15 = 11 - x
4x = -4
x = -1

how would you suggest going about this? I dont plan to write it in C, I was acctually going to write it in Visual Basic, but you are good with math, so I was curious how you would suggest doing it. So far I've created a type structure array to store all the monomials, but how do you suggest processing it, I'm stumpted. If you want to throw out some C code, I can port it to VB.

Question by:BrianGEFF719
LVL 84

Expert Comment

ID: 10910362
Will the problems be single variable linear equations like your example?

Expert Comment

ID: 10910474
Can we lowly creatures also participate in this question or you want only sunny's suggestion???
LVL 19

Author Comment

ID: 10914018
Everyone feel free to comment.

Right now I am going to focus on Single Variables.
How your wiki can always stay up-to-date

Quip doubles as a “living” wiki and a project management tool that evolves with your organization. As you finish projects in Quip, the work remains, easily accessible to all team members, new and old.
- Increase transparency
- Onboard new hires faster
- Access from mobile/offline

LVL 84

Expert Comment

ID: 10914618
If your problems will all be single variable linear equations you could just change = to -
evaluate at two x values, then extrapolate to where the expression equals 0
LVL 84

Expert Comment

ID: 10914637
(3x + 15) - (11 - x)
(3*0 + 15) - (11 - 0) = 4
(3*1 + 15) - (11 - 1) = 8
x = 4/(4-8) = -1
LVL 10

Expert Comment

ID: 10915044
To make it simple (e.g. without going to RPN resolution etc...) you have to get 4 variables
v1 is the number of x on left side
v2 is the number on left side (no x)
v3 is the number of x on right side
v4 is the number on right side (no x)

    e.g.  for 3x + 15 = 11 - x

    v1 = 3
    v2 = 15
    v3 = -1
    v4 = 11

The you calculate
     vx = v1 - v3
     vn = v4 - v2

And you have your result R = vn / vx

   vx = v1 - v3 = 4
   vn = -4
   R = 4 / -4 = -1

How to proceed programmatically (automat)
1 -   initialize all v1,v2,v3,v4 to 0.
2 -   parse the equation left side for v1, v2
3 -   set default sign is "+"
4 -   you get a sign : set sign to + or -
5 -   you get a number : put the number in N
6 -   number is followed by x : do v1 = v1 + N
7 -   number is not followed by x : do v2 = v2 + N
8 -   repeat from 3 etc...

Do the same right side, the vars being v3,v4
Once you get all v1...v4, calculate R as above.
LVL 10

Accepted Solution

Mercantilum earned 500 total points
ID: 10915054
of course of steps 5 and 6, N is signed by 'sign' (ie  N = N * sign ), sign being 1 if "+", -1 if "-"

Featured Post

Find Ransomware Secrets With All-Source Analysis

Ransomware has become a major concern for organizations; its prevalence has grown due to past successes achieved by threat actors. While each ransomware variant is different, we’ve seen some common tactics and trends used among the authors of the malware.

Join & Write a Comment

An Outlet in Cocoa is a persistent reference to a GUI control; it connects a property (a variable) to a control.  For example, it is common to create an Outlet for the text field GUI control and change the text that appears in this field via that Ou…
Preface I don't like visual development tools that are supposed to write a program for me. Even if it is Xcode and I can use Interface Builder. Yes, it is a perfect tool and has helped me a lot, mainly, in the beginning, when my programs were small…
Video by: Grant
The goal of this video is to provide viewers with basic examples to understand and use nested-loops in the C programming language.
The goal of this video is to provide viewers with basic examples to understand how to create, access, and change arrays in the C programming language.

708 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

21 Experts available now in Live!

Get 1:1 Help Now