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test_quad.bas
| Uploader: |  Volta |
| Datum/Zeit: | 30.09.2010 20:39:49 |
'PROGRAM test_quad
' Three tests of the basic quadruple precision module.
' 1. (A + B)^2 = (A - B)^2 + 4.A.B
' 2. (A^2 - B^2) / (A - B) = A + B
' 3. SQRT(A^2 + 2.A.B + B^2) = A + B
#Include "quad_1x.bi"
Using quad_precision
Screen 0
Width 90,40
Color 15,1
Cls
'' This captured from fortran code:
#define EPSILON_HALF 2.22044604925031308E-016
Print EPSILON_HALF
'' This derived by trial and error:
Print 2^-52
Print
Randomize 4711
'' I used this to verify that my code was producing random quads
'' in the same general range as the fortran test code. It does,
'' but I still don't understand why this range was chosen.
Dim As quad r, mn, mx
mn = 2000000000.0
For i As Integer = 1 To 1000000
r.hi = Rnd
r.hi = (r.hi-0.5) / r.hi
r.lo = r.hi * EPSILON_HALF
If r < mn Then mn = r
If r > mx Then mx = r
Next
Print "min = ";mn
Print "max = ";mx
Print
Dim As quad a, b, lhs, rhs, diff
For i As Integer = 1 To 10
a.hi = Rnd
a.hi = (a.hi-0.5) / a.hi
a.lo = a.hi * EPSILON_HALF
b.hi = Rnd
b.hi = (b.hi-0.5) / b.hi
b.lo = b.hi * EPSILON_HALF
'' (A + B)^2 = (A - B)^2 + 4.A.B
lhs = (a + b) * (a + b)
rhs = a * b
rhs = 4.0 * rhs
rhs = (a - b) * (a - b) + rhs
diff = lhs - rhs
Print "lhs = ";lhs,"diff = ";diff
'' (A^2 - B^2) / (A - B) = (A + B)
lhs = (a*a - b*b) / (a - b)
rhs = a + b
diff = lhs - rhs
Print "lhs = ";lhs,"diff = ";diff
'' SQRT(A^2 + 2.A.B + B^2) = A + B
lhs = a * b
lhs = 2.0 * lhs
lhs = Sqr(a*a + lhs + b*b)
If rhs.hi < 0 Then
rhs = -rhs
End If
diff = lhs - rhs
Print "lhs = ";lhs,"diff = ";diff
Next
Sleep