Wrong binary expression with double

[inf2405]

Hi :)

I am trying to implement a numerical approximation, but first I need to define the function and its first derivative. This is my code for the first derivative:

double Runge_der(double x)
{
double y=-(50*x)/(((25*x*x)+1)^2);
return y;
}

It shows a mistake in the definition of y, as "invalid operands to binary expression (double and double)", but I can't really find where the mistake is, because having first defined the original function as:


double Runge(double x)
{
double y;
y=1/((25*x*x)+1);
return y;
}

I didn't get any problems. If you could help me realize where the problem is, it would be extremely helpful.
Thanks :)

[Ganado]

^ does not mean exponentiation. In C++ and other similar languages (like Python, Java, C#), it means binary XOR (exclusive OR).

Change ((25*x*x)+1)^2
to pow(25*x*x + 1, 2)
or (25*x*x + 1)*(25*x*x + 1)
or equivalent.

If you use pow, #include <cmath> .

[AbstractionAnon]

double y=-(50*x)/(((25*x*x)+1)^2);
______________________________^

^ is the XOR operator, not an exponentiation operator.

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