what does function mean in the following context? 'The future value of every investment is a function of its present price'. The above sentence comes from Benjamin Graham's masterpiece 'The Intelligent Investor'. So could you help me understand the word 'function' in the sentence. I guess function here means ' a variable quantity regarded in relation to one or more other variables in terms of which it may be expressed or on which its value depends', a mathematical usage. But I couldn't get the relationship between 'future value of every investment' and 'its present price'. Does it mean the future value of every investment is influenced by its present price in a mathematical way? Thank you for your help.