Kahan summation: Difference between revisions

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 {{out}}<pre>Simple:  1.00000E +4 +  3.14159E +0 +  2.71828E +0 =  1.00058E +4
 Kahan :  1.00000E +4 +  3.14159E +0 +  2.71828E +0 =  1.00059E +4</pre>
+=={{header|C++}}==
+{{trans|C++}}
+<lang cpp>#include <iostream>
+float epsilon() {
+    float eps = 1.0f;
+    while (1.0f + eps != 1.0f) eps /= 2.0f;
+    return eps;
+}
+float kahanSum(std::initializer_list<float> nums) {
+    float sum = 0.0f;
+    float c = 0.0f;
+    for (auto num : nums) {
+        float y = num - c;
+        float t = sum + y;
+        c = (t - sum) - y;
+        sum = t;
+    }
+    return sum;
+}
+int main() {
+    using namespace std;
+    float a = 1.f;
+    float b = epsilon();
+    float c = -b;
+    cout << "Epsilon      = " << b << endl;
+    cout << "(a + b) + c  = " << (a + b) + c << endl;
+    cout << "Kahan sum    = " << kahanSum({ a, b, c }) << endl;
+    return 0;
+}</lang>
+{{out}}
+<pre>Epsilon      = 5.96046e-08
+(a + b) + c  = 1
+Kahan sum    = 1</pre>
 =={{header|C#|C sharp}}==