function [b, errstr, errid, msgObj] = isfdtbxinstalled
%ISFDTBXINSTALLED   Returns true if filter design toolbox is installed.

%   Copyright 1988-2019 The MathWorks, Inc.

persistent isinstalled

% Cache the results of ISTBXINSTALLED for performance
if isempty(isinstalled)
    isinstalled = istbxinstalled('dsp','dsp/filterdesign');
end

b = isinstalled && istbxlicensed('Signal_Blocks');
if b
    errstr = '';
    errid  = '';
    msgObj = message.empty;
else
    msgObj = message('signal:sigtools:noDSP');
    errstr = getString(msgObj);
    errid  = 'noDSP';
end
% [EOF]
