added another project

README.md

@@ -327,6 +327,9 @@ instructions. The program will "throw darts at a target," calculating
 an approximation of PI by tracking how many darts "hit the target"
 versus the total number of darts "thrown".
 
+The [SINE](./projects/SINE/README.md) project stresses floating point
+math and functions.
+
 The [SNOW](./projects/snow/README.md) project uses 1970's era tech to
 animate a simple particle system. This project demonstrates a reasonable
 design process of breaking down complex problems into simpler parts.

projects/README.md

@@ -8,5 +8,6 @@ Here are a number of challenges for you to flex your new found knowledge.
 | [FIRST](./first_project/README.md) | A good first project. |
 | [FIZZBUZZ](../section_1/fizzbuzz/) | The interview question. A video is also provided. |
 | [PI](./PI/README.md) | Compute an approximation of PI using stochastic (random) methods. |
+| [SINE](./SINE/README.md) | Stresses functions and floating point math. |
 | [SNOW](./snow/README.md) | A fun little animation. |
 | [WALKIES](./walkies/README.md) | A fun little animation. |

projects/SINE/README.md

@@ -0,0 +1,77 @@
+# Compute Sine using Taylor Series
+
+## Overview
+
+This project stresses the use of floating point instructions to create
+a program that computes the sine of an angle given to you in degrees
+on the command line.
+
+## Taylor Series
+
+The sine of an angle given in radians can be found using the Taylor
+Series:
+
+```text
+sin x = x - x^3/3! + x^5/5! - x^7/7! ...
+```
+
+Notice each term flips from addition to subtraction.
+
+Notice each term is based on the odd integers starting at 1.
+
+## Command line
+
+You are to accept two arguments on the command line. `getopt` is not
+being used here to concentrate on the floating point math. Both
+arguments are therefore required.
+
+* The angle in degrees whose sine you wish to calculate. Take this to
+  be a double.
+
+* The number of terms to evaluate. The number of terms must lie between
+  1 and 10 inclusive.
+
+## C version
+
+To assist your efforts, [here](./c_version.c) is a version of this
+project written in C.
+
+## Errors to stderr
+
+Error messages must be sent to `stderr`.
+
+If you are using the convergence macros to allow your program to build
+on both Apple Silicon Mac OS and Linux, note the special casing needed
+to deal with `stderr`. If this is you, compile the C version on Mac OS
+with the `-S` compiler option to see the generated assembly language and
+search for `stderr`.
+
+## Sample executions
+
+```text
+SINE % ./a.out 0 8
+The sine of 0.00 degrees is 0.000000 in radians.
+SINE % ./a.out 90 8
+The sine of 90.00 degrees is 1.000000 in radians.
+SINE % ./a.out 180 8
+The sine of 180.00 degrees is -0.000001 in radians.
+SINE % ./a.out 180 82
+Number of terms is out of range.
+SINE % ./a.out 180 -10
+Number of terms is out of range.
+SINE % echo $?
+1
+```
+
+## CSC3510
+
+The following applies to Carthage College CSC3510 students.
+
+### Work rules
+
+Work is to be done solo.
+
+### What to hand in
+
+Just the .S file. **Your name must be at the top of the file.**
+

projects/SINE/c_version.c

@@ -0,0 +1,67 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+double pi = 3.14159265359;
+
+double D2R(double d) {
+    return d * pi / 180.0;
+}
+
+long Factorial(int n) {
+    long retval = 1;
+
+    if (n > 0) {
+        while (n > 1) {
+            retval = retval * n--;
+        }
+    }
+    return retval;
+}
+
+double IntegerPower(double b, int e) {
+    double retval = 1.0;
+    if (e > 0) {
+        while (e > 0) {
+            retval = retval * b;
+            e--;
+        }
+    }
+    return retval;
+}
+
+
+int main(int argc, char ** argv) {
+    double sin = 0.0;
+
+	if (argc != 3) {
+		fprintf(stderr, "Two numerical arguments must be given.\n");
+        return 1;
+	}
+
+	double angle = atof(argv[1]);
+    int terms = atoi(argv[2]);
+
+    if (terms < 1 || terms > 10) {
+        fprintf(stderr, "Number of terms is out of range.\n");
+        return 1;
+    }
+
+    double r_angle = D2R(angle);
+
+    for (int term = 0, base = 1; term < terms; term++, base += 2) {
+        double toggle = (term & 1) ? -1.0 : 1.0;
+
+		sin += toggle *
+			   IntegerPower(r_angle, base) / Factorial(base);
+        /*
+		if (toggle > 0) {
+			printf("adding      %d p/b intermediate: %f\n", base, sin);
+		} else {
+			printf("subtracting %d p/b intermediate: %f\n", base, sin);
+		}
+        */
+	}
+	printf("The sine of %.2f degrees is %f in radians.\n", angle, sin);
+
+    return 0;
+}