Casio FX-991ES User Guide - Page 39

k Σ Calculations With Σ(, you can obtain the sum of an input f(x) expression for a specific range. Σ calculations are performed using the following formula. Σ( f(x), a, b) = f(a) + f(a + 1) + .... + f(b) f(x): Function of X (All non-X variables are treated as constants.) a: Calculation range start point b: Calculation range end point • a and b are integers in the range of -1 × 1010 < a < b < 1 × 1010. • The calculation step is fixed at 1. • ∫(, d/dx(, Pol(, Rec(, and Σ( cannot be used within f(x), a, or b. • Pressing A will interrupt an ongoing Σ calculation. Appendix Σ (X + 1, 1, 5) = 20 k Rectangular-Polar Coordinate Conversion Rectangular Coordinates (Rec) Polar Coordinates (Pol) • Coordinate conversion can be performed in the COMP, STAT, MATRIX, and VECTOR calculation modes. Converting to Polar Coordinates (Pol) Pol(X, Y) X: Specifies the rectangular coordinate X value Y: Specifies the rectangular coordinate Y value • Calculation result θ is displayed in the range of -180° < θ < 180°. • Calculation result θ is displayed using the calculator's default angle unit. • Calculation result r is assigned to variable X, while θ is assigned to Y. Converting to Rectangular Coordinates (Rec) Rec(r,θ) r : Specifies r value of polar coordinate θ : Specifies θ value of polar coordinate • Input value θ is treated as an angle value, in accordance with the calculator's default angle unit setting. • Calculation result x is assigned to variable X, while y is assigned to Y. E-37