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I am developing a mathematical parser which is able to evaluate String like '5+b*sqrt(c^2)'. I am using ANTLR for the parsing and make good progress. Now I fell over the Java class BigDecimal and thought: hey, why not thinking about precision here.
My problem is that the Java API does not provide trigonometric methods for BigDecimals like java.lang.Math. Do you know if there are any good math libraries like Apache Commons out there that deal with this problem?
The other questions is how to realize the power method so that I can calculate 4.9 ^ 1.4 with BigDecimals. Is this possible?
A book request about numerical computing is also appreciated.
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Math. sin() Method : is an inbuilt method which returns the sine of the value passed as an argument. The value passed in this function should be in radians.
I know that BigDecimal is more precise than double and you should use the former for calculations.
lang. Math. cos() returns the trigonometric cosine of an angle. If the argument is NaN or an infinity, then the result returned is NaN.
sin() returns the trigonometry sine of an angle in between 0.0 and pi. If the argument is NaN or infinity, then the result is NaN. If the argument is zero, then the result is a zero with the same sign as the argument.
ApFloat is a library which contains arbitrary-precision approximations of trigometric functions and non-integer powers both; however, it uses its own internal representations, rather than BigDecimal and BigInteger. I haven't used it before, so I can't vouch for its correctness or performance characteristics, but the api seems fairly complete.
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BigDecimal does not provide these methods because BigDecimal models a rational number. Trigonometric functions, square roots and powers to non-integers (which I guess includes square roots) all generate irrational numbers.
These can be approximated with an arbitrary-precision number but the exact value can't be stored in a BigDecimal. It's not really what they're for. If you're approximating something anyway, you may as well just use a double.
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The big-math library provides all the standard advanced mathematical functions (pow, sqrt, log, sin, ...) for BigDecimal.
https://github.com/eobermuhlner/big-math
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