Update usage/syntax

2 files changed, 7 insertions, 5 deletions

diff --git a/README.md b/README.md
index 29337bc..2cf16e7 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,9 @@ This is a tiny program which will output a binary [PGM](https://wikipedia.org/wi
 Syntax
 ------
 
-    ./mandelbrot-gen <size> <max_iterations> <power> [threads] > output.pgm
+    ./mandelbrot-gen -c size -i max_iterations -e exponent \
+                     [-c cores] [-t thread_multiplier]
+                     [-N cluster-id -T cluster-total] > output.pgm
 
 Also check out the other algorithms like `tricorn-gen` and `burning-ship-gen`.
 You might then want to consider using a tool such as ImageMagick to then convert the (large) output file into something more sane like a PNG.
diff --git a/fractal-gen.c b/fractal-gen.c
index 56163ea..c647ad5 100644
--- a/fractal-gen.c
+++ b/fractal-gen.c
@@ -192,7 +192,6 @@ bool args_parse_okay(int argc, char **argv)
 			/* redundant case for '?', but explicitness is best */
 			case '?':
 			default:
-				show_help();
 				return false;
 				break;
 		}
@@ -248,7 +247,8 @@ generator_func select_generator(const char* name)
 void show_help()
 {
 	fprintf(stderr,
-			"%s size iterat power [threads]\n"
-			"%s size iterat power thread_multiplier cluster-id cluster-total\n",
-			argv0, argv0);
+			"%s -s size -i iterat -e exponent\n"
+			"        [-c cores] [-t thread_multiplier]\n"
+			"        [-N cluster-id -T cluster-total]\n",
+			argv0);
 }