Expressing mathematical relationships?

Hi Folks,

Is there any XML technology that is intended for declaratively
expressing mathematical relationships, e.g., 

   Din = 2.54*Dcm (Din = distance in inches
                   Dcm = distance in centimeters)

   Tc = (5/9)*(Tf-32); (Tc = temperature in degrees Celsius, 
                        Tf = temperature in degrees Fahrenheit)

   etc.

Is MathML intended for this?  How about RuleML?

/Roger