## 2.2 Numerical Values

### 2.2.1 Constants and Other Stuff

• Some basic definitions,

numeric - a literal numerical value

variable - a symbol used to represent a quantity that will change, often represented with a lower case symbol

constant - a value that will not change, often represented with an upper case symbol

subscripts - letters or numbers below a variable to create new (related) variables.

• greek letters are often used for variables and constants • The constants listed are some of the main ones, other values can be derived through calculation. • In Scilab ### 2.2.2 Factorial

• A compact representation of a series of increasing multiples. ### 2.2.3 Significant Figures

• Sig figures rules,

- leading zeroes do not count as significant figures.

- trailing zeros will count as significant figures.

- when doing multiplying the results should will (generally) have the same number of significant figures as the least significant number.

- when adding, the least accurate number determines the accuracy of the result. • In computation the standard is to keep all of the digits, but the final answer should be rounded to the correct number of significant figures

• Based upon the accuracy of most measuring instruments, and the ability to specify components, most engineering calculations will have 3-6 significant figures. Do not use all of the digits produced by computer/calculator unless all of the digits can be justified.

### 2.2.4 Scientific and Engineering Notations

• In scientific notation one digit is ahead of the decimal, and all other values follow the decimal. The exponent is adjusted accordingly. • Scilab • Engineering notation is similar to scientific notation, but the exponent is always a multiple of 3 so that it corresponds to magnitude multipliers (i.e., micro, milli, kilo, mega). • The current version of Scilab does not seem to support engineering notation.