I have a co-variance matrix of variables like this: The values are mirror image across diagonal line. Therefore below diagonal or upper diagonal can be made null for convenience. This is variance-co-variance matrix of the coefficients of a linear regression. Obs Intercept length diameter height weight_w weight_s 1 0.15510 -0.29969 -0.05904 -0.20594 0.07497 -0.00168 2 -0.29969 3.46991 -3.50836 -0.01703 -0.04841 -0.14048 3 -0.05904 -3.50836 5.08407 -0.82108 -0.13027 0.10732 4 -0.20594 -0.01703 -0.82108 4.89589 -0.29959 0.30447 5 0.07497 -0.04841 -0.13027 -0.29959 0.13787 -0.18763 6 -0.00168 -0.14048 0.10732 0.30447 -0.18763 0.40414 Where Obs 1 – 6 represent Intercept, and five variables length, diameter, height, weight_w, weight_s. Diagonal values are variances. Rest are co-variances between variables and variables and intercept. I want to create a formula, where number of variables can change and user can input those as parameters. Based on number of variables formula should dynamically expand or contract and calculate result. The formula for five variables will be like this: C1,C2, ...C5 are constant that comes with five variables from outside. These are beta co-efficient of a linear regression. These will vary based on number of variables. 0.15+(C1)^2 * 3.46 + (C2)^2 * 5.08 + (C3)^2 * 4.89 + (C4)^2*0.13 + (C5)^2*0.40 -- Covers all variances +2*C1*-0.29 + 2*C2*-0.05 + 2*C3*-0.20 + 2*C4*-0.07 + 2*C5*-0.001 -- covers co-variance of all variables with intercept +2*C1*C2*-3.50 + 2*C1*C3*-0.01 + 2*C1*C4*-0.04 + 2*C1*C5*-0.14 --covers co-variance of “length” with other leftover (minus intercept) variables +2*C2*C3*-0.82+ 2*C2*C4*-0.13 + 2*C2*C5*0.10 -- covers co-variance of “diameter” with leftover variables +2*C3*C4*-0.29+ 2*C3*C5*0.30 -- covers co-variance of “height” with leftovers +2*C4*C5*-0.18 Those five constants, matching to five variables, are inserted from outside. Rest are coming from co-variance matrix. In the co-variance matrix table the diagonal values are variances of those variables. Rest are co-variances. In the formula, you can see that where there are variances I have taken square of constants (Cs). Where there are co-variance, of two variables involved, the respective constants (Cs) multiple. Intercept is another term that comes with these variables. But intercept doesn't have any "C". For two variables the co-variance matrix will be like this: Intercept will be there too. Obs Intercept GRE GPA 1 1.15582 -.000281894 -0.28256 2 -0.00028 0.000001118 -0.00011 3 -0.28256 -.000114482 0.10213 Formula for calculation: 1.15582+(C1)^2 * 0.000001118 + (C2)^2 * 0.10213 -- Covers all variances on diagonal line +2*C1*-.000281894 + 2*C2*-0.28256 -- covers co-variance of all variables with intercept +2*C1*C2*-0.00011 -- covers co-variance between variable GRE & GPA   ... View more