You can't get a lot for free these days never mind professional software. So we're really excited to be able to give you PTC Mathcad Express free of charge. It is the free-for-life version of PTC Mathcad Prime 3.1, the latest greatest release of the most powerful technical calculations software on planet earth.

With your free license, you get the most popular capabilities of PTC Mathcad for solving, documenting, sharing and reusing vital engineering calculations.

Write and edit mathematical equations and formulas in a full WYSIWYG environment using standard, natural notation.
Present calculations and designs by integrating live math, text, plots and images in one comprehensive document.
Hide complex or detailed information in collapsible areas.
Calculate common engineering problems using over 200 mathematical functions and operators.
Rely on PTC Mathcad's unit checking capability to avoid unit errors and ensure accuracy of results.
Visualize data and functions using X-Y plots.
If you download and choose the trial option, your first 30 days will include full PTC Mathcad capabilities:

Solving advanced engineering problems with over 400 functions in probability, statistics, data and analysis.
Programming allows you to group a set of calculation operations and return only the results you specify. When you assign a program to a function, you can call the program, use it, and plot its output.
Evaluate expressions and functions without the need to assign numerical values to variables. Keywords and modifiers control form and content of the displayed result, and integrate numeric and symbolic computation.
Integrate Excel functionality directly into worksheets easily with PTC Mathcad. With the Excel component, you can leverage tabular data presentation in your worksheet by using Excel's calculation and formatting tools inside PTC Mathcad.
Visualize 3D data sets and functional models with polar, contour and surface plots. PTC Mathcad makes it easy to get a quick qualitative and quantitative understanding of your models and data.
When the 30-day trial period has ended, you automatically continue using PTC Mathcad Express for an unlimited time.