# Turbo Pascal 7.0 Guide

Built-In Arithmetic Functions

The **sqrt() **function is built into the Pascal programming language. The format of this function is as follows,

`myroot :=`**sqrt**(mysquare)

The variables *myroot *and *mysquare *have been previously declared as real and integer respectively. In this example, mysquare is the **parameter **sent to the function. The real variable, *myroot *is assigned the value **returned **by the function.

Function | Description | Parameter Type | Return Value Type |
---|---|---|---|

abs(x) | absolute value of x (removes the sign) | integer or real | same as x |

arctan(x) | Inverse tangent of x (in radians) | integer or real | real |

cos(x) | Cosine of x (in radians) | integer or real | real |

exp(x) | Exponential function of x (ex) | integer or real | real |

ln(x) | Natural logarithm of x | integer or real | real |

round(x) | x rounded to the nearest integer | real | integer |

sin(x) | sine of x (in radians) | integer or real | real |

sqr(x) | x2 | integer or real | same as x |

sqrt(x) | square root of x | integer or real | real |

trunc(x) | x rounded to its integer part | real | integer |

To convert from degrees to radians, multiply by PI/180. To convert from radians to degrees, multiply by 180/PI.

General purpose high-level languages tend not to include an exhaustive list of trigonometric functions. Most other functions can be derived from the ones in the list above.

## Random Numbers

Computers cannot generate actual random numbers. The term **pseudorandom **is used to reflect the fact that the numbers appear random.

The built-in function **RANDOM**, returns a pseudorandom number.

x:= RANDOM | random number in the range 0<=x<1 |

x:= RANDOM(RANGE) | random number in the range 0<=x<RANGE |

In order to ensure that the 'random' numbers are not predictable in a program, we use the **RANDOMIZE **function at the beginning of the program. Random numbers are generated from a seed value. The randomize function changes the seed value for random numbers based on the current value of the computer's clock.

## Example Program

`PROGRAM lottery;`

VAR a: integer;

BEGIN

randomize;

a:= trunc(random(49)) +1;

writeln(a);

readln;

END.

## Exercises

- Write a program to simulate the throwing of 2 dice.
- Write a program which allows the user to input the length of 2 sides of a triangle. Use Pythagoras's theorem to find the length of the longest side.