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*/
// Test special cases for(int i = 0; i < testCases.length; i++) {
failures += testLog10Case(testCases[i][0],
testCases[i][1]);
}
// Test log10(10^n) == n for integer n; 10^n, n < 0 is not // exactly representable as a floating-point value -- up to // 10^22 can be represented exactly double testCase = 1.0; for(int i = 0; i < 23; i++) {
failures += testLog10Case(testCase, i);
testCase *= 10.0;
}
// Test for gross inaccuracy by comparing to log; should be // within a few ulps of log(x)/log(10) for(int i = 0; i < 10000; i++) { double input = Double.longBitsToDouble(rand.nextLong()); if(! Double.isFinite(input)) continue; // avoid testing NaN and infinite values else {
input = Math.abs(input);
double expected = StrictMath.log(input)/LN_10; if( ! Double.isFinite(expected)) continue; // if log(input) overflowed, try again else { double result;
if( Math.abs(((result=Math.log10(input)) - expected)/Math.ulp(expected)) > 3) {
failures++;
System.err.println("For input " + input + ", Math.log10 was more than 3 ulps different from " + "log(input)/log(10): log10(input) = " + result + "\tlog(input)/log(10) = " + expected);
}
if( Math.abs(((result=StrictMath.log10(input)) - expected)/Math.ulp(expected)) > 3) {
failures++;
System.err.println("For input " + input + ", StrictMath.log10 was more than 3 ulps different from " + "log(input)/log(10): log10(input) = " + result + "\tlog(input)/log(10) = " + expected);
}
}
}
}
// Test for accuracy and monotonicity near log10(1.0). From // the Taylor expansion of log, // log10(1+z) ~= (z -(z^2)/2)/LN_10;
{ double neighbors[] = newdouble[40]; double neighborsStrict[] = newdouble[40]; double z = Double.NaN;
// Test inputs greater than 1.0.
neighbors[0] = Math.log10(1.0);
neighborsStrict[0] = StrictMath.log10(1.0);
double input[] = newdouble[40]; int half = input.length/2;
// Initialize input to the 40 consecutive double values // "centered" at 1.0. double up = Double.NaN; double down = Double.NaN; for(int i = 0; i < half; i++) { if (i == 0) {
input[half] = 1.0;
up = Math.nextUp(1.0);
down = Math.nextDown(1.0);
} else {
input[half + i] = up;
input[half - i] = down;
up = Math.nextUp(up);
down = Math.nextDown(down);
}
}
input[0] = Math.nextDown(input[1]);
for(int i = 0; i < neighbors.length; i++) {
neighbors[i] = Math.log10(input[i]);
neighborsStrict[i] = StrictMath.log10(input[i]);
// Test accuracy.
z = input[i] - 1.0; double expected = (z - (z*z)*0.5)/LN_10; if ( Math.abs(neighbors[i] - expected ) > 3*Math.ulp(expected) ) {
failures++;
System.err.println("For input near 1.0 " + input[i] + ", Math.log10(1+z) was more than 3 ulps different from " + "(z-(z^2)/2)/ln(10): log10(input) = " + neighbors[i] + "\texpected about = " + expected);
}
if ( Math.abs(neighborsStrict[i] - expected ) > 3*Math.ulp(expected) ) {
failures++;
System.err.println("For input near 1.0 " + input[i] + ", StrictMath.log10(1+z) was more than 3 ulps different from " + "(z-(z^2)/2)/ln(10): log10(input) = " + neighborsStrict[i] + "\texpected about = " + expected);
}
// Test monotonicity if( i > 0) { if( neighbors[i-1] > neighbors[i] ) {
failures++;
System.err.println("Monotonicity failure for Math.log10 at " + input[i] + " and prior value.");
}
if( neighborsStrict[i-1] > neighborsStrict[i] ) {
failures++;
System.err.println("Monotonicity failure for StrictMath.log10 at " + input[i] + " and prior value.");
}
}
}
}
return failures;
}
publicstaticvoid main(String... argv) { int failures = 0;
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