Make a graph from formulas

Goal: draw one or more functions, for example sin(x) and cos(x), over a range you choose.

Steps

1. Open ALF > Content Creation > Graphs.

   

2. In step 1 Data, select Formulas.

3. Under Variable and range, set:

   • Variable: the name in your formulas, x by default (or n for sequences);
   • From, To and Step: the values it runs through;
   • Angles: Radians (sin(pi/2) = 1) or Degrees (sin(90) = 1).

4. Type a formula, and give it a Name. Press + Add a formula for each further line in the graph.

5. Check the Preview. Mistakes are explained under the formula, for example Did you mean sin(x)?.

6. Press Compute and add the graph to the scene.

Then continue with Choose the chart, Change the look and Place the graph, and press Save the scene in step 5 Save.

Writing formulas

You write	Meaning
+ - * / ^	Add, subtract, multiply, divide, power. ·, ×, ÷ and : work too.
2x, 3x^2, (x-1)(x+1)	Multiplication without a sign.
x², x³, √x, 5!	Square, cube, square root, factorial.
pi, π, e	Constants.
sin cos tan asin acos atan	Trigonometry, in radians or degrees as chosen.
sqrt abs ln exp floor ceil round	Common functions.
log(x), log(x, b)	Logarithm to base 10, or to base b.
min(a, b), max(a, b), mod(a, b)	Smallest, largest, remainder.
sum(k, 1, n, 1/k^2)	Sum over k from 1 to n, for series. prod(…) works the same for products.

Use a decimal point: 0.5, not 0,5.

Good to know

• Gaps are fine. Where a formula has no value, such as sqrt(x) below 0 or 1/x at 0, the line simply has a gap.
• Change the formulas later with Change the formulas… on the selected graph.
• The values are computed once and stored, like an imported file.