These two objects allow that we can treat all information related to certain data as one single ``variable'', and set the properties in a simple way. A good example is the command plot(obj) which plots the contents of any object in a reasonable form.
fiddata(frdobj) converts a Frequency Response Data object of the Control System Toolbox to an fiddata object, and frd(fobj) does the conversion in the other direction.
Here are a few examples based on the present implementation.
tdat = tiddata(randn(5,1),2*randn(5,1),100); get(tdat) Version = 1.1 Date = '20-Aug-1998 19:45:46' Input = [5x1 double] Output = [5x1 double] InputCharacter = 'ZOH' OutputCharacter = 'Samples' Ts = 100 ChNumber = 2 ExpNumber = 1 SampleNumber = 5 tdat.fs = 150; fs = tdat.fs fs = 150 set(tdat) Name: string Version: version number, set by the system Date: string (date + time) Notes: string History: cell array of strings Instrumentation: structure UserData: user-defined Input: [1x62 char] Output: [1x63 char] InputName: cell array of strings OutputName: cell array of strings InputCharacter: [1x62 char] OutputCharacter: cell array, [ 'Samples' | 'AASamples' ] InputUnit: cell array of strings OutputUnit: cell array of strings PeriodLength: positive scalar, maybe NaN Ts: scalar or cell array TStart: scalar or cell array SampleTimes: vector or cell array fdat = fiddata(ones(5,1),1./(1+j*2*pi*[1:5]'),[1:5]'); get(fdat) Version = 1.1 Date = '20-Aug-1998 19:55:10' Input = [5x1 double] Output = [5x1 double] InputCharacter = 'AASamples' OutputCharacter = 'AASamples' InputFreqPoints = [5x1 double] OutputFreqPoints = [5x1 double] FreqPoints = [5x1 double] AllFreqPoints = [5x1 double] FreqIndices = [5x1 double] ChNumber = 2 ExpNumber = 1 FreqNumber = 5 set(fdat) Name: string Version: version number, set by the system Date: string (date + time) Notes: string History: cell array of strings Instrumentation: structure UserData: user-defined Input: [1x62 char] Output: [1x63 char] InputName: cell array of strings OutputName: cell array of strings InputCharacter: [1x62 char] OutputCharacter: cell array, [ 'Samples' | 'AASamples' ] InputUnit: cell array of strings OutputUnit: cell array of strings PeriodLength: positive scalar, maybe NaN InputFrequencies: vector or cell array OutputFrequencies: vector or cell array Frequencies: vector or cell array State: cell array, [ 'transient' | 'steady-state' ] Synchronization: string, [ 'on' | 'off' ] InputFreqPoints: vector or cell array of vectors OutputFreqPoints: vector or cell array of vectors FreqPoints: vector or cell array of vectors InputDelay: array OutputDelay: array Fs: scalar InputVariance: vector (SISO) or cell array (MIMO) OutputVariance: vector (SISO) or cell array (MIMO) Covariance: 3-dimensional array, 3rd index: all freq points CovVector: vector (SISO) Coherence: 3-dimensional array, 3rd index: all freq points CohVector: vector (SISO)