Say you have the values;
matrix_of_interest = [986 120 0; 981 -60 0; 984 -60 0]
You need to multiply grams with 1/1000 to get kg (SI) , mm with 1/1000 to get m (SI). You can't convert grams to force, they are different units. But, if gravitational acceleration is say 9.81 m/s^2, 1g would mean 9.81/1000 Newtons of force acting on that one gram mass. You probably already knew these. To get the converted matrix, you need to multiply the elements of your inital matrix with these conversion factors element-wise (see https://www.mathworks.com/help/matlab/ref/times.html)
format long
converted_values = matrix_of_interest.*[(1/1000)*(0.001) 9.81/1000 (1/1000)*(0.01)]
