use named structs in small algebra system.

README.md

@@ -341,4 +341,10 @@ It emits one warning about something I already took care of, so by default I've
 - [x] Have some more complicated & realistic example
 - [x] Add summarization functions: 90% ci (or all c.i.?) 
 - [x] Link to the examples in the examples section.
-- [x] Add a few functions for doing simple algebra on normals, and lognormals?
+- [x] Add a few functions for doing simple algebra on normals, and lognormals
+  - [x] Add prototypes
+  - [x] Use named structs
+  - [ ] Test results
+  - [ ] Provide example
+  - [ ] Add to headers
+  - [ ] Move to own file

squiggle.c

@@ -437,44 +437,44 @@ struct c_i get_90_confidence_interval(double (*sampler)(uint64_t*), uint64_t* se
 }
 
 // Do algebra over lognormals and normals
-struct normal_parameters {
+typedef struct {
     double mean;
     double std;
-};
+} normal_parameters;
 
-struct lognormal_parameters {
+struct {
     double logmean;
     double logstd;
-};
+} lognormal_parameters;
 
-struct normal_parameters algebra_sum_normals(struct normal_parameters a, struct normal_parameters b)
+normal_parameters algebra_sum_normals(normal_parameters a, normal_parameters b)
 {
-    struct normal_parameters result = {
+    normal_parameters result = {
         .mean = a.mean + b.mean,
         .std = sqrt((a.std * a.std) + (b.std * b.std)),
     };
     return result;
 }
-struct normal_parameters algebra_shift_normal(struct normal_parameters a, double shift)
+normal_parameters algebra_shift_normal(normal_parameters a, double shift)
 {
-    struct normal_parameters result = {
+    normal_parameters result = {
         .mean = a.mean + shift,
         .std = a.std,
     };
     return result;
 }
 
-struct lognormal_parameters algebra_product_lognormals(struct lognormal_parameters a, struct lognormal_parameters b)
+lognormal_parameters algebra_product_lognormals(lognormal_parameters a, lognormal_parameters b)
 {
-    struct lognormal_parameters result = {
+    lognormal_parameters result = {
         .logmean = a.logmean + b.logmean,
         .logstd = sqrt((a.logstd * a.logstd) + (b.logstd * b.logstd)),
     };
     return result;
 }
-struct lognormal_parameters algebra_scale_lognormal(struct lognormal_parameters a, double k)
+lognormal_parameters algebra_scale_lognormal(lognormal_parameters a, double k)
 {
-    struct lognormal_parameters result = {
+    lognormal_parameters result = {
         .logmean = a.logmean + k,
         .logstd = a.logstd,
     };