add a few macros and functions

math.gs

@@ -39,6 +39,22 @@
 # Return `BASE` raised to the power of `EXP`.
 %define POW(BASE,EXP) antiln(ln(BASE)*(EXP))
 
+# Return the sign of `VALUE` (-1 when negative, 1 when positive, and 0 if 0)
+%define SIGN(VALUE) ((VALUE > 0) - (VALUE < 0))
+
+func safepow(base, exp) {
+    return POW(abs($base), $exp) * (2 * not($base < 0 and $exp % 2) - 1);
+}
+
+func atan2(y, x) {
+    # It is better to make it a function since it uses the arguments multiple times
+    # formula from https://en.wikipedia.org/wiki/Atan2
+    return 2 * atan((MAG($x, $y) - $x) / $y);
+}
+
+# Get the direction to (`X`, `Y`) from (`CX`, `CY`)
+%define DIR(X,Y,CX,CY) atan (((X)-(CX)) / ((Y)-(CY))) + 180 * ((CY) > (Y))
+
 # Gamma correct `VALUE` with power 2.2
 %define GAMMA(VALUE) antiln(ln(VALUE)/2.2)
 

string.gs

@@ -437,4 +437,13 @@ func countchars(text, chars) {
     return count;
 }
 
+func zfill(text, zeroes) {
+    local ret = $text;
+
+    repeat $zeroes - length $text {
+        ret = "0" & ret;
+    }
+    return ret;
+}
+
 %undef strbuf

test/test.gs

@@ -47,6 +47,15 @@ proc test {
     ASSERT_EQ(MAP(0, 1, 50, 100, 0.5), 75, "MAP(0, 1, 50, 100, 0.5)");
     ASSERT_EQ(RAD("90"), PI/2, "RAD(90)");
     ASSERT_EQ(DEG(PI/"2"), 90, "DEG(PI/2)");
+    ASSERT_EQ(SIGN(123), 1, "SIGN(123)")
+    ASSERT_EQ(SIGN(0), 0, "SIGN(0)")
+    ASSERT_EQ(SIGN(-456), -1, "SIGN(-456)")
+    ASSERT_EQ(safepow(3, 4), 81, "safepow(3, 4)")
+    ASSERT_EQ(safepow(-3, 3), -27, "safepow(-3, 3)")
+    ASSERT_EQ(safepow(4, -2), 0.0625, "safepow(4, -2)")
+    ASSERT_EQ(atan2(5, 4), 51.34019174590991, "ATAN2(5, 4)")
+    ASSERT_EQ(DIR(50, 50, 25, 25), 45, "DIR(50, 50, 25, 25)")
+
     # string
     ASSERT_EQ(countchar("AAA", "A"), 3, "countchar(...)");
     ASSERT_EQ(countchar("AAA", "B"), 0, "countchar(...)");
@@ -96,6 +105,7 @@ proc test {
     ASSERT_EQ(truncate("Hello world!", 12), "Hello world!", "1 shorten(...)");
     ASSERT_EQ(truncate("Hello world!", 11), "Hello ...", "2 shorten(...)");
     ASSERT_EQ(truncate("Hello world!", 10), "Hello...", "3 shorten(...)");
+    ASSERT_EQ(zfill("ABC", 6), "000ABC", "zfill(\"ABC\", 6)")
     # list
     split "5,3,1,2,4", ",";
     INSERTION_SORT(split);