Renee Baecker

# NAME

Math::Intersection::StraightLine - Calculate intersection point for two lines

version 0.05

# SYNOPSIS

``````  use Math::Intersection::StraightLine;
use Data::Dumper;
my \$finder = Math::Intersection::StraightLine->new();

# one intersection point
my \$vector_a = [[20,60],[-40,0]];
my \$vector_b = [[50,80],[0,50]];
my \$result = \$finder->vectors(\$vector_a,\$vector_b);
print Dumper(\$result);

# no intersection point
my \$point_a = [[20,60],[30,10]];
my \$point_b = [[50,80],[50,75]];
\$result = \$finder->point_limited(\$point_a,\$point_b);
print Dumper(\$result);``````

# DESCRIPTION

This module calculates the intersection point of two straight lines (if one exists). It returns 0, if no intersection point exists. If the lines have an intersection point, the coordinates of the point are the returnvalue. If the given lines have infinite intersection points, -1 is returned. Math::Intersection::StraightLine can handle four types of input:

## functions

Often straight lines are given in functions of that sort: y = 9x + 3

## vectors

the vector assignment of the line

``````  (10)     +     lambda(30)
(20)                 (50)``````

## points

The straight lines are described with two vectors to points on the line

``````  X1 = (10)             X2 = (40)
(20)                  (70)``````

## point_limited

If the module should test, if an intersection point of two parts exists

``````  X1 = (10)             X2 = (40)
(20)                  (70)``````

The following example should clarify the difference between `points` and `point_limited`:

``````  \$line_a = [[20,60],[30,10]];
\$line_b = [[50,80],[50,75]];
\$result = \$finder->points(\$line_a,\$line_b);

\$line_a_part = [[20,60],[30,10]];
\$line_b_part = [[50,80],[50,75]];
\$result = \$finder->point_limited(\$line_a_part,\$line_b_part);``````

The first example returns the intersection point 50/-90, the second returns 0 because `\$line_a_part` is just a part of `\$line_a` and has no intersection point with the part of line b.

In the first example, the lines are changed to the vectors of the lines.

# EXAMPLES

``````  \$vector_a = [[20,60],[30,10]];
\$vector_b = [[50,80],[60,30]];
\$result = \$finder->point_limited(\$vector_a,\$vector_b);
ok(\$result == 0,'parallel lines(diagonal)');

\$vector_a = [[20,60],[20,10]];
\$vector_b = [[60,80],[20,10]];
\$result = \$finder->vectors(\$vector_a,\$vector_b);
ok(\$result == -1,'overlapping vectors');

\$vector_a = [[20,60],[30,10]];
\$vector_b = [[50,80],[50,75]];
\$result = \$finder->points(\$vector_a,\$vector_b);
ok(\$result->[0] == 50 && \$result->[1] == -90,'Lines with one intersection point');

# test y=9x+5 and y=-3x-2
my \$function_one = [9,5];
my \$function_two = [-3,-2];
\$result = \$finder->functions(\$function_one,\$function_two);``````

# MISC

Note! The coordinates for the intersection point can be imprecise!

``````  # test y=9x+5 and y=-3x-2
my \$function_one = [9,5];
my \$function_two = [-3,-2];
\$result = \$finder->functions(\$function_one,\$function_two);``````

returns

``````  \$VAR1 = [
'-0.583333333333333', # this is imprecise
'-0.25'
];``````

# OTHER METHODS

## new

returns a new object of `Math::Intersection::StraightLine`

# AUTHOR

Renee Baecker <reneeb@cpan.org>

``  The Artistic License 2.0 (GPL Compatible)``