How can I change the mantissa size?

I have to do some calculation with different word size. One calculation with 7 bit mantissa and another with 10 bit mantissa How can I change the mantissa size for this calculation and to make proper floating point arithmetic?

The function : digits is not good for me or maybe I don't use it wright but the function limit the decimal accuracy, and what I need is to change the word size (mantissa size) which is binary

any suggestion? thanks!!!

[Stephen23]

Note that the mantissa is the fractional part of a logarithm. The significand is the part of a number containing the significant digits.

Answer 1

[Stephen23]

Maybe these will be helpful:

https://www.mathworks.fr/matlabcentral/newsreader/view_thread/251900

http://www.mathworks.fr/help/fixedpoint/ref/fi.html

[Vla]

Thanks but it is fixed point function I have to do my calculation with floating point arithmetic