Cubic Equation Solver


This page contains a routine that solves a Cubic Equation.

The utility posted on this page is a Javascript translation of the FORTRAN routine RPOLY.FOR, which is posted off the NETLIB site as TOMS/493. Although all care has been taken to ensure that the sub-routines were translated accurately, some errors may have crept into the translation. These errors are mine; the original FORTRAN routines have been thoroughly tested and work properly. Please report any errors to the webmaster.

Once the problem is arranged into the following form (a, b, c, and d are known constants), the equation can be solved for values of x that satisfy the equation.

a x 3   +   b x 2   +   c x   +  d   =   0

Since the equation is a third degree equation (the equation's highest power is three), there will be three solutions.

Input the values for a, b, c, and d below, and then click the "Calculate Solutions" button to have the results calculated.
NOTE: The solutions may include a non-zero imaginary component, as indicated by the "i" field.
Also, note the Error Code output.

Error Code   > 0:   Specifies the number of zeros found


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