Indcum
indcum is a short integer variable used as a default index by the sigma function. It is only relevant when a single sigma loop is used; otherwise, you need to name the variable used as a sigma index.
Syntax
indcumExamples
# Let's compute a (very) approximated value of pi
# The loop value cannot exceed 32,767 (short integer value)
Local Decimal APPROX_PI
APPROX_PI=4*sigma(0,1000,((-1)^indcum)/(2*indcum+1))
# Let's compute a (much better) approximated value of pi (David and Gregory Chudnovsky)
# Due to the factorials and exponentiation used here, you cannot exceed 3 for the loop
# Otherwise you will get a numeric overflow
APPROX_PI=1/(12*sigma(0,3,((-1)^indcum)*fac(6*indcum)*(13591409+(545140134*indcum))
& /(fac(3*indcum)*((fac(indcum))^3)*(640320^(3*indcum+3/2)))))
# Let's get the 26 letters in Latin alphabet
LETTERS=sigma(65,90,chr$(indcum))
# Sum of the square numbers of the integers from one (1) to N
SQUARE_SUM = sigma(1, N, indcum*indcum)Comments
Using indcum in a sigma expression performs faster than using a numeric variable.