Integral of $$$\cos{\left(x^{2} \right)}$$$

This integral (Fresnel Cosine Integral) does not have a closed form:

$${\color{red}{\int{\cos{\left(x^{2} \right)} d x}}} = {\color{red}{\left(\frac{\sqrt{2} \sqrt{\pi} C\left(\frac{\sqrt{2} x}{\sqrt{\pi}}\right)}{2}\right)}}$$

Therefore,

$$\int{\cos{\left(x^{2} \right)} d x} = \frac{\sqrt{2} \sqrt{\pi} C\left(\frac{\sqrt{2} x}{\sqrt{\pi}}\right)}{2}$$

Add the constant of integration:

$$\int{\cos{\left(x^{2} \right)} d x} = \frac{\sqrt{2} \sqrt{\pi} C\left(\frac{\sqrt{2} x}{\sqrt{\pi}}\right)}{2}+C$$

$$$\int \cos{\left(x^{2} \right)}\, dx = \frac{\sqrt{2} \sqrt{\pi} C\left(\frac{\sqrt{2} x}{\sqrt{\pi}}\right)}{2} + C$$$A