MathU™ RPN 2.2 for iPhone
Documentation
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Scientific Functions
The scientific functions in the table below are grouped by the number of values they use for their computation. The unary functions operate on the value in the x register and replace it with the function result (f(x))
while the binary functions use the values in both the x and y registers and place the result in the x register.
| Key | Function | Description | Type |
|---|---|---|---|
| f | f shift. Use to access functions above each button. | ||
| g | g shift. Use to access the functions at bottom of each button. | ||
| MOD | mod | Modulo remainder (y - x * floor(y/x)) | binary |
| π | pi | Value of pi | unary |
| LN | ln | Natural logarithm (base e) | unary |
| LOG | log | Base 10 logarithm | unary |
| ex | exp | Exponential function | unary |
| 10x | pow10 | Ten to the x power | unary |
| yx | ytox | y to the power of x | binary |
| x2 | sq | Square | unary |
| √x | sqrt | Square root | unary |
| 1/x | inv | Reciprocal | unary |
| FRAC | frac | Fractional part | unary |
| INT | int | Integer part | unary |
| n! | fact | Factorial (Gamma function) | unary |
The INT and FRAC functions round to 9 decimal digits before determining the integer and fractional parts. Under this definition FRAC is computed using the formula
frac(x) = x - int(x)
Most of the time this produces the desired results but does treat the input as if it only had 10 digits of accuracy. One of the ramifications of this is that the fractional part doesn't always have the same sign as x. Take for example the number 1.99999999964 (i.e. 2.0 - 3.6e-10). When displayed in MathU RPN this number looks like it is 2.0. Because of the rounding int(x) is 2 (as expected) while frac(x) is -3.6e-10.
The percent and %T act a little differently. They use the values in both x and y for the computation but leave the y value untouched.
| % | % | Percent (y * x) / 100 | binary |
| %T | %T | Percent of total 100 * x / y | binary |
This makes it easy to compute a percentage markup and net amount using %
Example 1: What is a 20% markup and net amount on $1,200?
- 1 2 0 0 to enter the base amount
- ENTER to separate the two numbers
- 2 0 to enter the percentage rate
- % to compute the markup. Ans: $240
- + to compute the net amount. Ans: $1,440
Example 2: What part of 150 is 35 and 10 (as a percentage)?
- 1 5 0 to enter the total (base) amount
- ENTER to separate the two numbers
- 3 5 to enter the first part
- %T to compute the first percent of total. Ans: 23.33%
- CLX to erase first answer and make room for second part. The next value entered will overwrite the x register without affecting the y register.
- 1 0 %T to compute the second percent of total. Ans: 6.67%