Mathcad is computer software for the verification, validation, documentation and re-use of mathematical calculations in engineering and science, notably mechanical, chemical, electrical, and civil engineering. Released in 1986 on DOS, it introduced live editing (WYSIWYG) of typeset mathematical notation in an interactive notebook, combined with automatic computations. It was originally developed by Mathsoft, and since 2006 has been a product of Parametric Technology Corporation. Mathcad was conceived and developed by Allen Razdow and Josh Bernoff at Mathsoft founded by David Blohm and Razdow. It was released in 1986. It was the first system to support WYSIWYG editing and recalculation of mathematical calculations mixed with text. It was also the first to check the consistency of engineering units through the full calculation. Other equation solving systems existed at the time, but did not provide a notebook interface: Software Arts' TK Solver was released in 1982, and Borland's Eureka: The Solver was released in 1987. Mathcad was acquired by Parametric Technology in April 2006. Mathcad was named "Best of '87" and "Best of '88" by PC Magazines editors. Mathcad's central interface is an interactive notebook in which equations and expressions are created and manipulated in the same graphical format in which they are presented (WYSIWYG). This approach was adopted by systems such as Mathematica, Maple, Macsyma, MATLAB, and Jupyter. Mathcad today includes some of the capabilities of a computer algebra system, but remains oriented towards ease of use and documentation of numerical engineering applications. Mathcad is part of a broader product development system developed by PTC, addressing analytical steps in systems engineering. It integrates with PTC's Creo Elements/Pro, Windchill, and Creo Elements/View. Its live feature-level integration with Creo Elements/Pro enables Mathcad analytical models to be directly used in driving CAD geometry, and its structural awareness within Windchill allows live calculations to be re-used and re-applied toward multiple design models.