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The ∏() Command

Command Summary Command Syntax Calculator Compatibility Token Size
Multiplies together the evaluations of an expression with one variable taking on a range of values. ∏(expression, variable, start, end) This command works on all calculators. 2 bytes
  • Press 2nd MATH to enter the MATH popup menu.
  • Press B to enter the Calculus submenu.
  • Press 5 to select ∏(.

The ∏() Command

∏() is used to multiply a sequence of numbers. ∏(expression, variable, start, end) will evaluate expression for variable=start, then for variable=start+1, all the way through variable=end, and multiply the results:

:∏(f(x),x,1,5)
           f(1)*f(2)*f(3)*f(4)*f(5)
:∏(x,x,1,5)
           120

In this way, ∏() is no different from taking 68k:product() of a sequence generated by 68k:seq(). However, ∏() can be used for more abstract calculations — for instance, when start or end is an undefined variable, it will try to find the product in terms of that variable. ∏() can also be used to find the product of an infinite series (just make the value of end infinity — ∞). 

:∏(x,x,1,n)
           n!
:∏(1-1/x,x,2,n)
           1/n
Authors: KG