Solve Blocks > TOL and CTOL
  
TOL and CTOL
TOL—Worksheet variable that controls the convergence precision of some functions such as integrals, derivatives, odesolve and the root functions.
CTOL—Worksheet variable that controls how closely a constraint in a solve block must be met for a solution to be acceptable when using find, minerr, minimize, or maximize. For example, if a constraint such as x < 2 must be satisfied to within CTOL before a solution is returned, and if CTOL = 0.001 (the default), then this constraint is satisfied when x < 2.001.
Additional Information
Smaller values of TOL produce more precise solutions, but may increase calculation time, or make it impossible for an operation to converge. An error message may appear when the numerical properties of the expression are such that a solution asymptotically approaches a number that exceeds the acceptance threshold set by TOL.
Tolerances for solve block constructs find, minerr, minimize and maximize are set internally. Unlike previous versions of PTC Mathcad, you no longer need to set TOL in a solve block.