funktions(maths)

Maximilian

Hej.
I'm trying to programm a program which shoud calculate funktions....
äm, i mean
the program shoud draw the graf of the funktion and find "zero-points" and the extrem-points....

but have anyone any idears how i shoud make the "input"... so i mean how shoud the user enter the funktion?

thanks for idears (:
Lg Maxi

5 Replies

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Vulpes14y ago
If you're using the second type (where the user selects a function type and then enters the coefficients), I'd be inclined to create a class for each function type so you can easily evaluate it for a given value of x.

For example, for a cubic function, you could create a Cubic class on the following lines:

public class Cubic
{
double a, b, c, d;

public Cubic(double a, double b, double c, double d)
{
this.a = a;
this.b = b;
this.c = c;
this.d = d;
}

public Cubic(string aStr, string bStr, string cStr, string dStr)
{
double.TryParse(aStr, out a);
double.TryParse(bStr, out b);
double.TryParse(cStr, out c);
double.TryParse(dStr, out d);
}

public double Evaluate(double x)
{
return a * x * x * x + b * x * x + c * x + d;
}
}

To use this, you could then do:

Cubic c = new Cubic(txtA.Text, txtB.Text, txtC.Text, txtD.Text);
// evaluate when x = 1
double value = c.Evaluate(1);

I've included a second constructor so you can pass it strings directly without having to parse them to numbers first. If one of the strings is an invalid number, then the corresponding coefficient will be given a value of 0 but you can change the code to throw an exception instead if you like.
Maximilian14y ago
oh yea, in German we write function with 'k'^^

okey,
but how can i analyse the string?

strig input = "f(x)=13x^3-2x^(1+1)+4x-43";

or how should I go ahead with the analyse of the txt?
copy the thing into int[] ant create an ArrayList for the sequence(?) and then do one task of the arrayList after another?

Lg
Roy S14y ago
So if I get this correct, you want to make a program where the user enters a function and the program should return the x-values of the function where the corresponding y-value is zero (those zero-points).

Personally I would choose the second type. It's easier and if that works you can always try doing the first type later.

Btw:'function' is with a 'c' not a 'k'.
Maximilian14y ago
yeah, sorry, it is hard to explain in english^^

withe Textbox & button (you have to wirte f(x) = 10x³+2x²-15x+9 into the textbox)

withe radio buttons and textboxes for the variables (you have to chose 1 funktion-type withe te radiobuttons, and then enter the values of the variables a,b,c....)

at first: should i take the first or the second type? or an other one, and which?
and how should i create the "text"-analyse if i chose the type with the tb?
...
Lg
Nitesh Kejriwal14y ago
Hey, Please explain your question in detail...Not sure what you mean by "how I should make the input""