D.14.8 mpfr conversion functions

The functions described in this section convert between mpfr numbers and character strings, naturals, or standard IEEE floating point format (in their list representations). Where these functions have similar or equivalent counterparts in the mpfr library’s native API, the names have been changed for mnemonic reasons.

dbl2mp

The input is a standard floating point number as in math. The result is an mpfr number equal to the input with a fixed precision, currently set to 160 bits.

mp2dbl

The input is an mpfr number, and the output is the best possible approximation to it by a standard a double precision number.

str2mp

The input is a pair (prec,s), where prec is a natural number specifying the precision, and s is a string expressing a floating point number in C format. The output is an mpfr number with the specified precision.

mp2str

The input is an mpfr number, and the output is a character string expressing the number in exponential decimal notation. Sufficiently many decimal digits are included in the string to express the full precision.

nat2mp

The input is a natural number represented as described in Representation of Numeric and Textual Data, and the output is an mpfr number of sufficient precision to express the natural number exactly.

The mp2str function enhances the native mpfr_get_str function by properly formatting the output string rather than only listing the digits of the mantissa.

The nat2mp function does not rely on the mpfr native integer conversion functions, so natural numbers with any number of bits up to MP_PREC_MAX can be used losslessly. There is currently no conversion in the other direction.

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