cos

→ cos()

Returns the cosine of an angle — a number that swings between -1 and 1.

cos(sekhutlo)

cos is a wave just like sin, but it starts somewhere else: cos(0) is 1, where sin(0) is 0. It is the same wave, shifted by a quarter turn.

That is why the two are used together to build a circle: cos gives x, and sin gives y.

cos is also reached for when you want a number that begins high and eases down — something opening, or fading out.

By default the angle is read in radians; seeloSaSekhutlo(DEGREES) changes that.

The name is left as it stands, for the same reason as sin: it is notation taught in English in a Botswana classroom.

Parameters

Name	Type	Description
`sekhutlo`	`palo`	The angle, in radians by default, or in degrees when `seeloSaSekhutlo(DEGREES)` is set.

Examples

A circle built from cos and sin

Open in editor ↗

tiro setaLoeto() {
  thalaKanefase(400, 400);
  bokamorago(20, 24, 32);
  tlogelaMothalo();

  metlha dintlha = 48;

  gopheta (diri i = 0; i < dintlha; i = i + 1) {
    // Go dikologa go go feletseng ke PEDI_PI diradiane
    metlha sekhutlo = selekanyo(i, 0, dintlha) * PEDI_PI;

    metlha x = 200 + cos(sekhutlo) * 140;
    metlha y = 200 + sin(sekhutlo) * 140;

    tlatsaMmala(lekanyetsa(cos(sekhutlo), -1, 1, 60, 250), 160, lekanyetsa(sin(sekhutlo), -1, 1, 250, 60));
    thalaSediko(x, y, 20);
  }
}

cos and sin start in different places

Open in editor ↗

tiro setaLoeto() {
  thalaKanefase(400, 400);
  bokamorago(244);
  boketeMothalo(3);

  // cos e simolola kwa godimo — cos(0) ke 1
  mothaloMmala(220, 120, 70);
  gopheta (diri x = 0; x < 400; x = x + 2) {
    thalaNtlha(x, 200 - cos(x * 0.025) * 110);
  }

  // sin e simolola fa gare — sin(0) ke 0
  mothaloMmala(60, 130, 210);
  gopheta (diri x = 0; x < 400; x = x + 2) {
    thalaNtlha(x, 200 - sin(x * 0.025) * 110);
  }
}

cos

Parameters

Examples

See also