LazStats: Add tests.

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@7925 8e941d3f-bd1b-0410-a28a-d453659cc2b4

applications/lazstats/tests/tdist_test/Project1.pas

@@ -0,0 +1,49 @@
+program Project1;
+
+uses
+  spe,
+  MathUnit;
+
+const
+  xmin = 0.0;
+  xmax = 3.0;
+  dx = 0.5;
+  DF = 10;
+
+procedure Test(s: Integer);
+var
+  i: Integer;
+  x, y_lazStats, y_numlib: Double;
+  ok: string;
+begin
+  WriteLn('Student''s t distribution with ', DF, ' degrees of freedom (', s, '-sided)');
+  WriteLn;
+  WriteLn('x':15, 'y(lazstats)':15, 'y(numlib)':15, 'OK':15);
+  x := xmin;
+  while (x <= xmax) do begin
+    if x < 0 then
+      y_numlib := 1.0 - spe.tDist(-x, DF, s)
+    else
+      y_numlib := spe.tDist(x, DF, s);
+
+    if x < 0 then
+      y_lazstats := 1.0 - mathunit.tDist(-x, DF, s=1)
+    else
+      y_lazstats := mathunit.tDist(x, DF, s=1);
+
+    if abs(y_lazstats - y_numlib) < 1E-6 then
+      ok := 'OK'
+    else
+      ok := 'ERROR';
+
+    WriteLn(x:15:5, y_lazstats:15:5, y_numlib:15:5, ok:15);
+    x := x + dx;
+  end;
+end;
+
+begin
+  Test(1);
+  Test(2);
+  ReadLn;
+end.
+