getFloat64 method
Returns the floating point number represented by the eight bytes at
the specified byteOffset
in this object, in IEEE 754
double-precision binary floating-point format (binary64).
Throws RangeError if byteOffset
is negative, or
byteOffset + 8
is greater than the length of this object.
Implementation
double getFloat64(int byteOffset, [Endian endian = Endian.big]);