User manual TEXAS INSTRUMENTS TI-25X SOLAR

[. . . ] When pressed once during a calculation (but before an operation key), clears the displayed entry and any error condition (E). Pressing does not clear the memory, statistics register, or angle-unit setting. Instructs the calculator to perform the second function (written above the key) of the next key pressed. ` 1 ENG The Display You can enter a maximum of eight digits in the display. Any digit key pressed after the eighth is ignored. Indicator ­ 2nd D R G () STAT K M E Meaning The displayed number is negative. [. . . ] You can store a number in memory for repeated use in a calculation or to keep a running total. Key Function Stores the displayed number in memory, replacing any previously stored number. The displayed number is stored, and the previously stored number is displayed. memory. 7 ENG Constant Calculations The constant key h simplifies repetitive calculations by storing a number and its associated operation for repeated use. After storing the constant, you can complete each repeated calculation by simply entering the new number and pressing l. To erase the constant, clear the calculator or enter any of the above arithmetic keys. Key mph m h mh m h m h 8 ENG Angle-Unit Setting Before starting a trigonometric calculation, use the key to select the appropriate angle-unit setting (D--Degree, R--Radian, or G--Grad). Key Function Changes the angle-unit setting without affecting the displayed angle value. Changes the angle-unit setting and converts the displayed angle value to its equivalent for the new setting. `x D 45. `x Trigonometric Functions Key , X, Function Calculates the sine, cosine, or tangent of the displayed angle. Example: 90 30 X l 0. 1339746 Calculates arcsine, arccosine, or arctangent of the displayed value. Example: 1 ` 90. ` ` ` , , 9 ENG Degree Format Conversions An angle measured in degrees, minutes, and seconds (DMS) must be converted to decimal degrees (DD) before you can use it in a calculation. Degrees, Minutes, and Seconds DMS angles are entered in D. MMSSsss format. MM SS sss Degrees (°)--0 to 8 digits Decimal point separator Minutes (')--must be 2 digits Seconds (")--must be 2 digits Fractional part of a second For example, enter 48°5'3. 5" as 48. 05035. ddddddd Degrees (°) Decimal point separator Fractional part of a degree For example, enter 34. 047° as 34. 047. 10 ENG Converting Angle-Measurement Format The TI 25X Solar can easily convert an angle measurement from one degree format to the other. Key ` [DMS8DD] Function Converts the displayed value from degrees, minutes, and seconds (DMS) to decimal degrees (DD). If necessary, include leading zeros as needed to place the digits in the proper positions. Converts the displayed value from decimal degrees (DD) to degrees, minutes, and seconds (DMS). Enter the angle in D. ddddddd format, and then press ` [DD8DMS]. ` [DD8DMS] Example: Convert 33°7'8" in DMS format to DD format and back to DMS format. Comments DMS format DD format DMS format Keystrokes 33. 0708 ` [DMS8DD] ` [DD8DMS] Display 33. 0708 33. 118889 33. 0708 11 ENG Rectangular-to-Polar Conversions Pressing ` [R8P] converts rectangular coordinates (x, y) to polar coordinates (r, ). [. . . ] Comments Clear display Clear register 1st entry 2nd entry 3rd entry (incorrect) 3rd entry (removed) 3rd entry (correct) 4th entry Mean (class average) Standard Deviation Variance Keystrokes ` [CSR] 96 81 97 97 ` 87 70 ` ` Display 0. 83. 5 9. 4472218 89. 25 Important: Remember to press ` [CSR] to clear the statistics register and return to arithmetic calculations. 14 ENG Error Conditions The display shows E when an error occurs or when you attempt certain operations. If the digits fail to appear on the display: Check to be sure that no part of the solar panel is covered. Review the operating instructions to be certain the calculations were performed properly. [. . . ]