/// <summary>
/// Nodes between two points, compressed at both ends
/// </summary>
/// <param name="l">lower limit.</param>
/// <param name="r">upper limit.</param>
/// <param name="a">scaling between linear ans sinus-mapping</param>
/// <param name="n">number of nodes</param>
/// <returns></returns>
public static double[] SinLinSpacing(double l, double r, double a, int n)
{
if (a < 0)
{
throw new ArgumentOutOfRangeException();
}
if (a > 1)
{
throw new ArgumentOutOfRangeException();
}
if (l >= r)
{
throw new ArgumentOutOfRangeException();
}
double[] linnodes = GenericBlas.Linspace(-Math.PI * 0.5, Math.PI * 0.5, n);
double[] linnodes2 = GenericBlas.Linspace(-1, 1, n);
double[] nodes = new double[n];
for (int i = 0; i < n; i++)
{
//nodes[i] = linnodes2[i] * (1 - a) + (1.0 - Math.Sin(linnodes[i])) * a;
nodes[i] = linnodes2[i] * (1 - a) + Math.Sin(linnodes[i]) * a;
}
for (int i = 0; i < n; i++)
{
nodes[i] = nodes[i] * (r - l) * 0.5 + (r + l) * 0.5;
//Debug.Assert(nodes[i] >= l);
//Debug.Assert(nodes[i] <= r);
}
return(nodes);
}
/// <summary>
/// <paramref name="a"/> = <paramref name="alpha"/>*<paramref name="B"/>
/// </summary>
static public void SetV <T, V>(this T a, V B, double alpha = 1.0)
where T : IList <double>
where V : IList <double> //
{
int N = a.Count;
if (B.Count != N)
{
throw new ArgumentException("element count must be equal");
}
if (object.ReferenceEquals(a, B))
{
// while formally there is no problem that this should work, it seems much more likely
// that it's a bug, i.e. the user called it un-intentionally.
throw new ArgumentException("Illegal use: reference-equality of input vectors -- this might be a mis-use instead of intention.");
}
a.ClearEntries();
GenericBlas.daxpy(N, alpha, B, 1, a, 1);
}
/// <summary>
/// scales some vector <paramref name="a"/> by scalar <paramref name="alpha"/>.
/// </summary>
static public void ScaleV <T>(this T a, double alpha) where T : IList <double>
{
GenericBlas.dscal(a.Count, alpha, a, 1);
}
