colorm.go
func (c *ColorM) Element(i, j int) float64 {
	b, t := c.impl.UnsafeElements()
	if j < ColorMDim-1 {
		return float64(b[i+j*(ColorMDim-1)])
	}
	return float64(t[i])
}
func (c *ColorM) Element(i, j int) float64 {
	b, t := c.impl.UnsafeElements()
	if j < ColorMDim-1 {
		return float64(b[i+j*(ColorMDim-1)])
	}
	return float64(t[i])
}
// Element returns a value of a matrix at (i, j).