Patent ID: 6895422

Claim:
A computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for finding the roots of a quadratic equation with interval coefficients, the method comprising: receiving a representation of the quadratic equation of the form F(x)=Ax 2 +Bx+C =0, wherein A, B and C are interval coefficients; wherein A is represented by a floating-point number, A L , for the left endpoint of A, and a floating-point number, A U , for the right endpoint of A; wherein B is represented by a floating-point number, B L , for the left endpoint of B, and a floating-point number, B U , for the right endpoint of B; wherein C is represented by a floating-point number, C L , for the left endpoint of C, and a floating-point number, C U , for the right endpoint of C; computing intervals containing roots of the functions F 1 (x), F 2 (x), F 3 (x) and F 4 (x), wherein F 1 (x)=A L x 2 +B L x+C L , F 2 (x)=A U x 2 +B U x+C U , F 3 (x)=A L x 2 +B U x+C L and F 4 (x)=A U x 2 +B L x+C U ; placing the computed intervals into a list, L; ordering the computed intervals in the list, L, so that a given entry, S i , is represented by a floating-point number, S iL , for the left endpoint of S i , and a floating-point number, S iU , for the right endpoint of S i , and wherein S iL≦S i+1,L ; and establishing interval roots for F(x) from the interval entries in list L.