# ExtractingCoordinatesFromPoint

## Extracting coordinates from a Point: PG Code Snippet

*This code snippet shows the essential PG code to evaluate antderivative and general antiderivative formulas. Note that these are insertions, not a complete PG file. This code will have to be incorporated into the problem file on which you are working.*

*This wiki page is under construction as of 6/13/08.*

PG problem file | Explanation |
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loadMacros("MathObjects.pl"); |
In the initialization section, we need to include the macros file |

Context( "Point" ); push(@point, Point(random(1,5,1), random(-5,-1,1))); push(@point, Point(random(5,10,1), random(6,11,1))); # now we have two points, $point[0] = (x1,y1) # and $point[1] = (x2,y2). # the following makes $d1 = x1 - x2, $d2 = y1 - y2 ($d1, $d2) = ($point[0] - $point[1])->value; $length = Compute("sqrt( ($d1)^2+($d2)^2 )"); $mid = ( $point[1] + $point[0] ) / 2; |
In the problem setup section of the file, we put the value of the subtraction of two Points in two variables, Alternative method: If you want to get only one of the coordinates of a Point, you can use the
We don't use Alternative method: You can use
We need to put parentheses around |

Context()->texStrings; BEGIN_TEXT Consider the two points \( $point[0] \) and \( $point[1] \). The distance between them is:\{ $length->ans_rule() \} $BR The midpoint of the line segment that joins them is:\{ $mid->ans_rule() \} $BR END_TEXT Context()->normalStrings; |
The problem text section of the file is as we'd expect. |

ANS( $length->cmp ); ANS( $mid->cmp ); |
As is the answer. |