View Compilation Error

0_0_13691932_4291.cpp: In function 'void circle_cross_line(point, point, point, double, point*, int&)':
0_0_13691932_4291.cpp:105:39: error: 'mysqrt' was not declared in this scope
         double t1 = (-B - mysqrt(delta)) / (2 * A);
                                       ^