Constrain input signal to zero
The Algebraic Constraint block constrains the input signal f(z) to zero and outputs an algebraic state z. The block outputs the value that produces a zero at the input. The output must affect the input through a direct feedback path, that is, the feedback path contains only blocks with direct feedthrough. For example, you can specify algebraic equations for index 1 differential-algebraic systems (DAEs).
The Algebraic Constraint block uses a dogleg trust-region algorithm to solve algebraic loops , .
The Algebraic Constraint block accepts and outputs real values
An initial guess for the solution value. The default is
By default, the Initial guess parameter is zero. You can improve the efficiency of the algebraic-loop solver by providing an Initial guess for the algebraic state z that is close to the solution value.
For example, the following model solves these equations:
z2 + z1 = 1 z2 - z1 = 1
The solution is
z2 = 1,
z1 = 0,
as the Display blocks show.
Inherited from driving block
 Garbow, B. S., K. E. Hillstrom, and J. J. Moré. User Guide for MINPACK-1. Argonne, IL: Argonne National Laboratory, 1980.
 Rabinowitz, P. H. Numerical Methods for Nonlinear Algebraic Equations. New York, NY: Gordon and Breach, 1970.