PartitionArithmetic.h

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#ifndef INTARNA_PARTITIONARITHMETIC_H_
#define INTARNA_PARTITIONARITHMETIC_H_
#include "IntaRNA/general.h"
#include <stdexcept>
 
namespace IntaRNA {
class PartitionArithmetic {
public:
    static Z_type check(const Z_type x);
    static Z_type add(const Z_type a, const Z_type b);
    static Z_type multiply(const Z_type a, const Z_type b);
    static Z_type divide(const Z_type a, const Z_type b);
    static Z_type exp(const Z_type exponent);
};
inline Z_type PartitionArithmetic::check(const Z_type x) {
    if (!(x>=0 && x<=std::numeric_limits<Z_type>::max())
            || (x>0 && x<std::numeric_limits<Z_type>::min()))
        throw std::range_error("partition arithmetic: numerical range exceeded");
    return x;
}
inline Z_type PartitionArithmetic::add(const Z_type a,const Z_type b) {
    return check(check(a)+check(b));
}
inline Z_type PartitionArithmetic::multiply(const Z_type a,const Z_type b) {
    check(a); check(b);
    if (a==0 || b==0) return 0;
    const Z_type r=check(a*b);
    if (r==0) throw std::range_error("partition arithmetic: product underflow");
    return r;
}
inline Z_type PartitionArithmetic::divide(const Z_type a,const Z_type b) {
    check(a); check(b);
    if (b==0) throw std::range_error("partition arithmetic: zero denominator");
    const Z_type r=check(a/b);
    if (a>0 && r==0) throw std::range_error("partition arithmetic: quotient underflow");
    return r;
}
inline Z_type PartitionArithmetic::exp(const Z_type exponent) {
    const Z_type r=check(Z_exp(exponent));
    if (r==0) throw std::range_error("partition arithmetic: exponential underflow");
    return r;
}
}
#endif