Be (somewhat more) consistent about the value of pi

Use M_PI (and friends), where possible, in favor of hand-coded
approximations of various (in)accuracies.  Where that's not available
(e.g. fragment shaders), use the same value that qmath.h uses for
M_PI, for consistency.  Replaced math.h with qmath.h in places that
defined a fall-back in case math.h omits it (it's not in the C++
standard, although M_PI is in POSIX); or removed this entirely where
it wasn't used.

Reworked some code to reduce the amount of arithmetic needed, in the
process; e.g. pulling common factors out of loops.  Revised an
example's doc to not waste time talking about using a six-sig-fig
value for pi (which we no longer do) - it really wasn't relevant, or
anything to be proud of; nor did the doc mention its later use.

Task-number: QTBUG-58083
Change-Id: I5a31e3a2b6a823b97a43209bed61a37b9aa6c05f
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 14 insertions, 15 deletions

diff --git a/tests/auto/corelib/kernel/qmath/tst_qmath.cpp b/tests/auto/corelib/kernel/qmath/tst_qmath.cpp
index ad40b0140d..feb704e0aa 100644
--- a/tests/auto/corelib/kernel/qmath/tst_qmath.cpp
+++ b/tests/auto/corelib/kernel/qmath/tst_qmath.cpp
@@ -30,8 +30,6 @@
 #include <QtTest/QtTest>
 #include <qmath.h>
 
-static const double PI = 3.14159265358979323846264338327950288;
-
 class tst_QMath : public QObject
 {
     Q_OBJECT
@@ -55,8 +53,9 @@ void tst_QMath::fastSinCos()
 {
     // Test evenly spaced angles from 0 to 2pi radians.
     const int LOOP_COUNT = 100000;
+    const qreal loopAngle = 2 * M_PI / (LOOP_COUNT - 1);
     for (int i = 0; i < LOOP_COUNT; ++i) {
-        qreal angle = i * 2 * PI / (LOOP_COUNT - 1);
+        qreal angle = i * loopAngle;
         QVERIFY(qAbs(qSin(angle) - qFastSin(angle)) < 1e-5);
         QVERIFY(qAbs(qCos(angle) - qFastCos(angle)) < 1e-5);
     }
@@ -69,18 +68,18 @@ void tst_QMath::degreesToRadians_data()
     QTest::addColumn<double>("degreesDouble");
     QTest::addColumn<double>("radiansDouble");
 
-    QTest::newRow( "pi" ) << 180.0f << float(M_PI) << 180.0 << PI;
-    QTest::newRow( "doublepi" ) << 360.0f << float(2*M_PI) << 360.0 << 2*PI;
-    QTest::newRow( "halfpi" ) << 90.0f << float(M_PI_2) << 90.0 << PI/2;
+    QTest::newRow( "pi" ) << 180.0f << float(M_PI) << 180.0 << M_PI;
+    QTest::newRow( "doublepi" ) << 360.0f << float(2 * M_PI) << 360.0 << 2 * M_PI;
+    QTest::newRow( "halfpi" ) << 90.0f << float(M_PI_2) << 90.0 << M_PI_2;
 
     QTest::newRow( "random" ) << 123.1234567f << 2.1489097058516724f << 123.123456789123456789 << 2.148909707407169856192285627;
     QTest::newRow( "bigrandom" ) << 987654321.9876543f << 17237819.79023679f << 987654321987654321.987654321987654321 << 17237819790236794.0;
 
     QTest::newRow( "zero" ) << 0.0f << 0.0f << 0.0 << 0.0;
 
-    QTest::newRow( "minuspi" ) << -180.0f << float(-M_PI) << 180.0 << PI;
-    QTest::newRow( "minusdoublepi" ) << -360.0f << float(-2*M_PI) << -360.0 << -2*PI;
-    QTest::newRow( "minushalfpi" ) << -90.0f << float(-M_PI_2) << -90.0 << -PI/2;
+    QTest::newRow( "minuspi" ) << -180.0f << float(-M_PI) << 180.0 << M_PI;
+    QTest::newRow( "minusdoublepi" ) << -360.0f << float(-2 * M_PI) << -360.0 << -2 * M_PI;
+    QTest::newRow( "minushalfpi" ) << -90.0f << float(-M_PI_2) << -90.0 << -M_PI_2;
 
     QTest::newRow( "minusrandom" ) << -123.1234567f << -2.1489097058516724f << -123.123456789123456789 << -2.148909707407169856192285627;
     QTest::newRow( "minusbigrandom" ) << -987654321.9876543f << -17237819.79023679f << -987654321987654321.987654321987654321 << -17237819790236794.0;
@@ -104,18 +103,18 @@ void tst_QMath::radiansToDegrees_data()
     QTest::addColumn<double>("radiansDouble");
     QTest::addColumn<double>("degreesDouble");
 
-    QTest::newRow( "pi" ) << float(M_PI) << 180.0f << PI << 180.0;
-    QTest::newRow( "doublepi" ) << float(2*M_PI) << 360.0f << 2*PI << 360.0;
-    QTest::newRow( "halfpi" ) << float(M_PI_2) << 90.0f<< PI/2 << 90.0;
+    QTest::newRow( "pi" ) << float(M_PI) << 180.0f << M_PI << 180.0;
+    QTest::newRow( "doublepi" ) << float(2 * M_PI) << 360.0f << 2 * M_PI << 360.0;
+    QTest::newRow( "halfpi" ) << float(M_PI_2) << 90.0f << M_PI_2 << 90.0;
 
     QTest::newRow( "random" ) << 123.1234567f << 7054.454427971739f << 123.123456789123456789 << 7054.4544330781363896676339209079742431640625;
     QTest::newRow( "bigrandom" ) << 987654321.9876543f << 56588424267.74745f << 987654321987654321.987654321987654321 << 56588424267747450880.0;
 
     QTest::newRow( "zero" ) << 0.0f << 0.0f << 0.0 << 0.0;
 
-    QTest::newRow( "minuspi" ) << float(-M_PI) << -180.0f << -PI << -180.0;
-    QTest::newRow( "minusdoublepi" ) << float(-2*M_PI) << -360.0f << -2*PI << -360.0;
-    QTest::newRow( "minushalfpi" ) << float(-M_PI_2) << -90.0f << -PI/2 << -90.0;
+    QTest::newRow( "minuspi" ) << float(-M_PI) << -180.0f << -M_PI << -180.0;
+    QTest::newRow( "minusdoublepi" ) << float(-2 * M_PI) << -360.0f << -2 * M_PI << -360.0;
+    QTest::newRow( "minushalfpi" ) << float(-M_PI_2) << -90.0f << -M_PI_2 << -90.0;
 
     QTest::newRow( "minusrandom" ) << -123.1234567f << -7054.454427971739f << -123.123456789123456789 << -7054.4544330781363896676339209079742431640625;
     QTest::newRow( "minusbigrandom" ) << -987654321.9876543f << -56588424267.74745f << -987654321987654321.987654321987654321 << -56588424267747450880.0;