**Table of Content**

**Search clouds**

**Licenses**

**Author's resources**

You are a guest. Restricted access. Read more.

Command disabled: recent

Numerous Java packages can be used to solve linear, non-linear and differential equations.

To solve linear, quadratic and cubic equations, use the jhplot.math.Numeric package. In general, only real solutions are considered.

from jhplot.math.Numeric import * a=solveLinear(1,2) # solves ax+b=0. a=1, b=2 print a b= solveQuadratic(1, 2, -1) # roots of the quadratic equation print b b= solveCubic(1, 2, 4,2) print b c=solveQuartic(1,-2, 3, 4, -2) print b

For solving polynomial equations, one can use the symbolic calculation engine. Read more in Sect.Analytic calculations

from jhplot.math import * from jhplot import * j=Symbolic("jscl") # using jscl engine j.expand("solve(c+b*x+a*x^2,x)") # answer: root[0](c, b, a)

One solve algebraic equation systems of any degree, with several indeterminates, by computing the Groebner bases of polynomial ideals. For example, let this system for the indeterminates x, y:

x^2 + y^2 = 4 x*y = 1

We use:

>>> j.expand("groebner({x^2 + y^2 - 4, x*y - 1}, {x, y})")

The returned output is:

{1-4*x^2+x^4, 4*x-x^3-y}

which allows to find x, then y from x. This operation doesn't calculate the roots, it just writes the equation. For example, it wouldn't give “a = 4/5” but “5*a-4” (“= 0” implied). Groebner basis computation is explained in more details below:

Consider a linear systems of equations of the form AX=B. For example, consider

2x + 3y - 2z = 1 -x + 7y + 6x = -2 4x - 3y - 5z = 1

We will solve this using DecompositionSolver of the Apache Common Math package:

from org.apache.commons.math3.linear import * # get the coefficient matrix A using LU decomposition coeff= Array2DRowRealMatrix([[2,3,-2],[-1,7,6],[4,-3,-5]]) solver =LUDecompositionImpl(coeff).getSolver() # use solve(RealVector) to solve the system constants = ArrayRealVector([1, -2, 1 ]) solution = solver.solve(constants); print "Solution: x=",solution.getEntry(0), "y=",solution.getEntry(1),"z=",solution.getEntry(2)

The execution of this code prints:

Solution: x= -0.369863013699 y= 0.178082191781 z= -0.602739726027

Read more for different types of decomposition here. Please read more the Linear algebra section.

You can solve non-linear equations using the jMathLab symbolic kernel as explained in Section Equations