remove no-longer used decomposeMatrix function

Author: dhowe

src/math/trigonometry.js

@@ -204,33 +204,6 @@ function trigonometry(p5, fn){
     return this._fromRadians(Math.asin(ratio));
   };
 
-  fn.decomposeMatrix = function(mat) {
-    // adapted from https://frederic-wang.fr/2013/12/01/decomposition-of-2d-transform-matrices/
-    let { a, b, c, d, e, f } = mat;
-    let delta = a * d - b * c;
-    let result = {
-      translation: { x: e, y: f },
-      scale: { x: 0, y: 0 },
-      shear: { x: 0, y: 0 },
-      rotation: 0
-    };
-    if (a !== 0 || b !== 0) {
-      let r = Math.sqrt(a * a + b * b);
-      result.rotation = b > 0 ? Math.acos(a / r) : -Math.acos(a / r);
-      result.scale = { x: r, y: delta / r };
-      result.shear = { x: Math.atan((a * c + b * d) / (r * r)), y: 0 };
-    } else if (c !== 0 || d !== 0) {
-      let s = Math.sqrt(c * c + d * d);
-      result.rotation = Math.PI / 2 -
-        (d > 0 ? Math.acos(-c / s) : -Math.acos(c / s));
-      result.scale = { x: delta / s, y: s };
-      result.shear = { x: 0, y: Math.atan((a * c + b * d) / (s * s)) };
-    } else {
-      // a = b = c = d = 0
-    }
-    return result;
-  };
-
   /**
    * Calculates the arc tangent of a number.
    *