Thread: mathematical equations

Hi,can anyone help me out how to accept mathematical equations involving log,cos,sin,e,etc. Whether I should use structure or array.Please let me know.I have been given a project to write a program for simpson's 1/3 rule and i am confused about how to accept those equations.
THANKS........

Post the whole description of the assignment. What you just posted gives very little information on what it is you need to do.

My program is to write an algorithm for simpson's 1/3 rule and hence a computer program to find the integral of a equation

integral from 4 to 5.2 for the equation (log(sin x))^2.

I want to know how to take this equation i.e.(log(sin x))^2 as an input in the program.I need to take the input in a structure or array, i m confused.
rest of the program i can do it but this initial part is compklex to me.....

A few things:

1) You seem to be confused about the difference between an algorithm and a computer program.

2) In order to read equation input like you want you need to produce some sort of syntax parser which is a very difficult task. You can't just take the input in a "structure or array". You need to take it as a string, parse it and make sense of the operations involved in it and their precedence, typically by using a stack.

I remember I wrote something similar to this some years back and it only accepted parantheses, basic operations and logarithms and it was a pain in the back to write. If you want to write something that parses any mathematical equation in C you are going to be coding for a loooong time.

If you are not restricted to using C perhaps Matlab or Mathematica would be more helpful here.

What is a syntax parser, can you explain me a bit?
And also you mean programs involving mathematical equations are very complex and not possible.........

Let me google that for you

Originally Posted by rakeshkool27

What is a syntax parser, can you explain me a bit?
And also you mean programs involving mathematical equations are very complex and not possible.........

I am certainly not implying it's impossible. But, it takes a lot of work to get there.

First of all you have to be familiar with grammars and how they work, preferably with BNF/EBNF notation, parse trees, etc. You should perhaps explore these topics first, before starting such a huge project.

Good luck

Originally Posted by brewbuck

I seriously want to know where people come up with this crap. REALLY.

"I want to write a program to do X. Is it possible?"

"I can't make the computer do Y. It must be impossible?"

Yeah man. It's the computer that's limited. Has nothing to do with the fact that you don't know anything yet. We landed robots on the planet Mars, which is amazing considering that programs "involving mathematical equations" are so complex that they simply aren't possible.

The Mars rovers shipped with basically a really good random number generator. Whenever the rover wants to do something it rolls the dice and prays (yes, we attached two mechanical hands to the back of it so that it can pray properly)

LOL. Good one!

The OP stated several times that he needs to take as input an equation (actually a mathematical function) so he is not solving a particular one. That requires parsing one way or another.

Well, regardless what he wants, he has not responded as of yet, so let's wait for his reply and I guess we will see which of the two he is actually referring to.

Originally Posted by MK27

No, he does not say that at all, except once hesitantly. In fact, what he does say quite clearly several times is that he needs to "write an algorithm for simpson's 1/3 rule" -- which would be a particular equation.

That does not requiring parsing.

Simpson's rule is most emphatically NOT a particular equation. It is an algorithm that takes a function as input -- hence the "I need to input a function" requirement -- and outputs an estimate of the integral of that function over a region. (The prototype would generally be something like

Code:

double simpson(double f(double), double start, double end, double tolerance);

although if you're feeling lucky you can make those floats.)

Now, when I assign this program, I make the students write some functions to integrate as sample (and of course I have mine that I use to test), so perhaps those auxiliary functions are all that is needed. But functions must be provided, one way or another.

I seriously want to know where people come up with this crap. REALLY.

"I want to write a program to do X. Is it possible?"

"I can't make the computer do Y. It must be impossible?"

Yeah man. It's the computer that's limited. Has nothing to do with the fact that you don't know anything yet. We landed robots on the planet Mars, which is amazing considering that programs "involving mathematical equations" are so complex that they simply aren't possible.

The Mars rovers shipped with basically a really good random number generator. Whenever the rover wants to do something it rolls the dice and prays (yes, we attached two mechanical hands to the back of it so that it can pray properly)

Everyone is not a born genius and you are also not an exception to this, brewbuck.
And I need not land robots on Mars now. If you dont wanna help please dont, but dont comment unnecessarily.