Mathcad
(ver 2.5)
Abandonware


Mathcad is mathematics software primarily intended for the validation, 
verification, documentation, and re-use of engineering calculations.  
Version 2.5 was the last DOS version.  

Mathcad claims that - "You use it the same way you learned how to 
do mathematical calculations in the first place: on a scratchpad.". 
You enter text, equations, functions, matrices, etc., in free form 
and answers are calculated automatically. Standard functions, matrices, 
statistical functions, curve-fitting, two and three dimensional plots, 
Fourier transforms, solving up to 50 simulataneous linear and nonlinear 
equations and inequalities with up to 50 variables, iterations, 
numerical integration, and differentiation, are some of its features.  

Mathcad saved files end with the ".MCD" extension.  These files MUST be 
in the same directory as the Mathcad executable, or they can't be found.
Some example *.MCD files have been included (press "F5" to load).  Note 
that *.MCD files are ASCII files that are readable with a Text viewer.