Waveform display device for displaying length by converting frequency into length on machined surface

A waveform display device, comprising:

• a processor configured to execute a program to
• acquire position information of a drive shaft of a machine tool in a time series manner;
• acquiring acquire physical data that represents an operation status of the drive shaft in a time series manner;
• designate a time section that is a display target in a time series of the physical data or the position information;
• calculate an average tangent direction speed of a tool tip end point of the machine tool in the time section based on the position information and configuration information of the machine tool;
• perform a frequency analysis of the physical data or the position information in the time section to output a frequency spectrum;
• and
• convert a frequency of the frequency spectrum into a distance between two points on a machined surface of the machine tool that corresponds to the frequency using the average tangent direction speed;
• and
• a display configured to display the distance between the two points.