# Shortcuts for elasticity of substitution

How can I find the elasticity of substitution (I know the definition) if I know the utility function $$u(x,y)$$? I know its increasing in $$x$$ and $$y$$, etcetera, and has everything else you want from a reasonable utility function. Is there a way to get the elasticity of substitution without the tedious algebra (writing $$x/y$$ as a function of mrs/price-ratio etc)?

• I have found a formula but it says divide by |BH| but it never says what that is. There was also no derivation so not sure if its actually correct. Has anybody heard of |BH|? – vroompie Jan 16 at 21:27