I started to learn C ++ recently and the skills are not very big yet, please help with the task, no matter how it is solved:

Find the root of the equation y = ax ^ 2sinx + b, provided that the root is unique and lies on the interval [x1, x2]. To find use the method of dividing the segment in half. The accuracy of the calculation is given by the value ε> 0 which determines the length of the interval containing the root.

Closed due to the fact that off-topic by pavel participants, Vladimir Martyanov , Nicolas Chabanovsky ♦ 29 Sep '16 at 5:09 .

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  • You definitely need to familiarize yourself with the part of the standard library math - Malov Vladimir
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1 answer 1

See - we have the equation y(x) = 0 . It is necessary to define this function.

 double y(double x) { // Тело напишите сами }

We have a segment on which we are looking. So? So there is

 double a,b;

(don't forget to initialize!). Next, we need to know the signs of the function values ​​at these points:

 double ya = y(a), yb = y(b);

It would be nice to check that they have different signs ...

Further we will work in a cycle, narrowing the segment. Those. until we get |ab| < eps |ab| < eps , or since we always have b > a , just ba < eps . Those.

 while(b - a > eps) {

And what is there? Delhi in half:

 double x = (a + b)/2;

and find the value of the function:

 double f = y(x);

Now let's see ... if it is of the same sign as a , we move a , if b is, respectively.

 if (ya * f >= 0) a = x; else b = x;

This cycle ends ...

And now collect all this in a heap, add what is missing, achieve that it is compiled, debug it (I could have missed a mistake ... :)) and carry it.

PS You did not really hope to get a finished job? :)

  • Thank you very much, no, of course, this is quite enough to understand where to go and how the code should work - Valery