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Mathematics Equation Solving Wolfram Language

Posted 3 years ago

POSTED BY: Zhenyu Zeng

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Posted 3 years ago

POSTED BY: Eric Rimbey

Posted 3 years ago

Okay. I am still confused but your answer helps me a lot.

POSTED BY: Zhenyu Zeng

Posted 3 years ago

If x is unassigned, then the expression `Sin[x]==0` cannot be evaluated further. That's just a consequence of the rules for Sin and Equal. So, it turns out that the immediate evaluation of `Sin[x]==0` effects no change to that expression. SetDelayed holds the right hand side unevaluated, but in this case, you get the same result whether you evaluate it or not. What Gianluca showed you illustrates the difference between Set and SetDelayed by making it possible to further evaluate `Sin[x]==0` (by assigning a value to x). In otherwords, the fact that OwnValues[test] is the same in both cases is a coincidence due to the particular expression you chose to assign to test.

POSTED BY: Eric Rimbey

Posted 3 years ago

Hello, Thanks for your reply. Set function is evaluated as it shows the first time. So, test=Sin[x]==0 will assign Sin[x]==0 to test. After this, I input x=pi, then I enter test the result are False. As Set function is evaluated as it shows the first time. So, test should always be Sin[x]==0. Why after I inputing x=pi, test becomes False?