GeoGebra Klaslokaal

# dynamic colors

## Introduction

Following applet illustrates two ways to use dynamic colors.
• The colors of the sign of a function f and the color of a Point P depent on a given condition.
• The colors of a slider s and a point C are calculated out of a variable value.
• sign of a function: The sign of a function f(x)= ax + b depends from the values of a and b.
• color of a point P: Point P colors green when it's on the graph of f and red if it's not.
• color of a slider: The color of slider s changes while moving the slider.
• color of a point C: The color of point P changes if you drag it along the segment l.

## How do you do this?

• Sign of the function f: Create: - a slider a from -4 to 4 with increment 0.5 - a slider b from-4 to 4 with increment 0.5 - a function f(x) = a x + b - a number zero = -b/a - a number c = Integral(f, -50, zero) - a number d = Integral(f, zero, 50) Open the Properties of c and d, select the tab Advanced and define their dynamic colors so that a negative value will color red and a positive value will color green.  ﻿ colors of c﻿ colors of d﻿ ﻿Red: If(c < 0, 1, 0) ﻿If(c > 0, 0.7, 0) ﻿Green: ﻿If(d < 0, 1, 0) ﻿If(d > 0, 0.7, 0) ﻿Blue: ﻿0 ﻿0
• Color of the point P: Create a point P, open its Properties and select the tab Advanced. Define its colors so that P colors green when it's on the graph and green when it's not.  ﻿Red: If(Distance(P, f) > 0, 1, 0)﻿ ﻿Green: ﻿If(Distance(P, f) ≟ 0, 0.7, 0) ﻿Blue: ﻿0
﻿
• Color of the slider s: Create a slider from 0 to 1 with increment 0.1. Define its color in the tab advanced of its Properties:  ﻿Red: ﻿s ﻿Green ﻿0 ﻿Blue ﻿1-s
Moving the slider from 0 to 1 its color will change from blue to red.
• Color of the point C: Create: - the Segment l between the points A and B: l = Segment(A,B). - the Point C on the segment. - the Segment g between the points A and C: g = Segment(A,C). Define its colors so that C will color from black to green while dragging it on the segment.  ﻿Red: ﻿0 ﻿Green: ﻿g/l ﻿Blue: ﻿0