How to convert each of the following mathematical expressions to its equivalent statement in C?
1 / (x^2 + y^2)
square root of (b^2 - 4ac)
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First you should try to learn the language you want to use. Then the answer will be trivial. some links that may help. http://www.cprogramming.com/tutorial/c/lesson1.html http://www.cs.cf.ac.uk/Dave/C/node17.html – reader_1000 Sep 07 '11 at 11:34
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1.0 / (pow(x,2) + pow(y,2))sqrt(pow(b,2) - 4*a*c)
See pow() and sqrt() functions manual.
You can also write x*x instead of pow(x, 2). Both will have the exact same result and performance (the compiler knows what the pow function does and how to optimize it).
(For commenters)
GCC outputs the exact same assembler code for both of these functions:
double pow2_a(double x) {
return pow(x, 2);
}
double pow2_b(double x) {
return x * X;
}
Assembler:
fldl 4(%esp)
fmul %st(0), %st
ret
Arnaud Le Blanc
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what's the benefit of not using it ? (given that it's a compiler intrinsic in most compilers) – Arnaud Le Blanc Sep 07 '11 at 11:33
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Are you suggesting that `pow(x, 2.0)` will be optimized to `x*x`? – Armen Tsirunyan Sep 07 '11 at 11:34
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Really does the compiler (let's say GCC and VC++) know how to optimize `pow(x, 2.0)` (because in C there is only the `double, double` "variant")? – xanatos Sep 07 '11 at 11:35
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2It's a more accurate translation of the source code (and better for teaching imo). Besides using `x * x` is a premature optimization (GCC 4.5.2 compiles `pow(x,2)` to `x*x` even without optimization enabled) – user786653 Sep 07 '11 at 11:35
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