Roots of a quadratic function: Difference between revisions
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'''Task''': do it better. This means that given <math>a = 1</math>, <math>b = -10^9</math>, and <math>c = 1</math>, both of the roots your program returns should be greater than <math>10^{-11}</math>. Or, if your language can't do floating-point arithmetic any more precisely than single precision, your program should be able to handle <math>b = -10^6</math>. Either way, show what your program gives as the roots of the quadratic in question. See page 9 of
[https://www.validlab.com/goldberg/paper.pdf "What Every Scientist Should Know About Floating-Point Arithmetic"] for a possible algorithm.
=={{header|11l}}==
<lang 11l>F quad_roots(a, b, c)
V sqd = Complex(b^2 - 4*a*c) ^ 0.5
R ((-b + sqd) / (2 * a),
(-b - sqd) / (2 * a))
V testcases = [(3.0, 4.0, 4 / 3),
(3.0, 2.0, -1.0),
(3.0, 2.0, 1.0),
(1.0, -1e9, 1.0),
(1.0, -1e100, 1.0)]
L(a, b, c) testcases
V (r1, r2) = quad_roots(a, b, c)
print(r1, end' ‘ ’)
print(r2)</lang>
{{out}}
<pre>
-0.666667+0i -0.666667+0i
0.333333+0i -1+0i
-0.333333+0.471405i -0.333333-0.471405i
1e+09+0i 0i
1e+100+0i 0i
</pre>
=={{header|Ada}}==
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