Using MathCAD SCC Spring-08 Electronic Technology Wang Ng x-2638

Overview About MathCAD Using MathCAD as an interactive calculator Using MathCAD with formulas Equation solver Convenient features Advanced features Example : AC calculations Conclusion

General features MathCAD –WYSIWYG –K to 4-year College level. –Simple, easy to use. –Not intended for heavy-duty number crunching. MatLab –Programming style. –Up to M.S. level –Extensive training required. –Suitable for heavy-duty number crunching.

Calculator Mode The Calculator Tool Bar The “=“ key (It is the output command) Examples:  1+1=2 1/3=0.333  sin(1)=0.841sin(1deg)=0.017  1mi=1931m1mi=6336ft  Interactive: just edit the numbers  sin(45deg)=0.707

Complex Calculations Use i or j for the imaginary part  (5+3j)+(2-4j)=(5+3j)-(2-4j)=  (5+3j)*(2-4j)=(5+3j)/(2-4j)=  (5+3j)^2= = Polar/Rectangular conversion:  |5+3j|=  arg(5+3j)=(type deg)  2e^45j*deg= “j” can be placed in front by typing: 1j*45deg

Formulas You need to provide data: use the “:” key as the input command (it will look like :=). Then you need to enter the formula. Use the “=“ key to obtain the result. Example: Enter the followings  E:3V  R:2   I:E/R  I=

Equation solver Find(x,y,...) Solves a system of equations. Minerr(x,y,...) Approximate solution to a system of equations. root(f(x),x,a,b) Solves one equation in one unknown. lsolve(M,v) Solves a system of linear equations. polyroots(v) Solves for the roots of the polynomial whose coefficients are in v.

Example: Using the “root” command

Convenient features Use the worksheet as handouts. Specify the unit of the results. Change the input data and the results will be updated automatically. Note: Data must be placed above formulas. Many built-in functions (root, …) Comments can be entered after the “ key. You can save the worksheet. Resource center: Tutorials, quick sheets, …

Advanced features Symbolic process: The symbolic menu bar –Examples: type x^2”space”-1”space” and then select “Factor” from the symbolic menu bar. Graphs: see attached Bode Plot example. Array and range variables: Use the “;” key. See attached example. Programming: The programming menu bar has the basic programming commands. Calculus, differential equations, matrices, optimization, statistics, …

Bode Plot Example

Examples: RLC circuit impedance R1 R2 R3 C1 C2 L

Conclusion MathCAD is a versatile teaching tool: Calculation steps (formulas) Demonstrate specific effects Graphics Exam/Homework problems Partial credit Course note