![]() ![]() With 32 decimal places calculations take 3-4 seconds. With the default of 12, trig functions calculate in about a second. The settings page allows the accuracy to be set from 6 to 32 decimal places. After setting accuracy to 24 places arcsin(arccos(arctan(tan(cos(sin(9)))))) evaluates to this: One way to measure the accuracy of calculations is with the calculator forensic found here. I was able to speed the shifting up even more by using another lookup table that let me right shift 4 digits at a time. Instead, a lookup table is used with adds and shifts, which are much faster. This is a very efficient way to compute these functions for processors that cannot multiply or divide quickly. The trig and log functions are computed using CORDIC routines. Unsigned char *text2=(unsigned char*)230 Unsigned char *text1=(unsigned char*)200 Here is an example:įor (int i=0 msg i++) putchar(msg) įor (int i=0 RAM_Read(msg+i) i++) putchar(RAM_Read(msg+i)) These are usually ignored by the compiler if they are not recognized, so they are a convenient way to communicate with the preprocessor. ![]() To mark variables as external, #pragma directives are used. External variables are all stored as pointers, so the PC version will work exactly the same with or without the preprocessor. To simplify things, I wrote a preprocessor program that looks for any variables that need to be stored in external RAM and converts access to them to function calls. Would become something like this (assuming we are passing pointers): I wanted to access this memory using variables but there is no convenient way to do this since every variable requires a function to access it. Numbers are stored in unpacked BCD format on an external SRAM chip. You can download it from GitHub if you want to test out the functionality: rpnmain_pc.c It will compile for Windows if #WINDOWS is defined or for Linux with the ncurses library if #LINUX is defined. While I was writing the code for BCD calculations, I used a console program to test the routines. The interface shows 4 levels of the stack, similar to some HP calculators. Functions: (a)sin, (a)cos, (a)tan, y^x, x root y, e^x, ln, 10^x, log, mod.Internal accuracy configurable from 6 to 32 decimal places.This is a scientific calculator I built that uses RPN notation.
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