Skip to content

complex: Fix expm1 formula computing exp(z-1) instead of exp(z)-1 #1601

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
duncanita wants to merge 1 commit into from
Closed

complex: Fix expm1 formula computing exp(z-1) instead of exp(z)-1 #1601

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 1 addition & 1 deletion src/complex.cc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1272,7 +1272,7 @@ COMPLEX_BODY(expm1)
// ----------------------------------------------------------------------------
{
complex_g one = complex::make(1, 0);
return exp(z - one);
return exp(z) - one;
}


Expand Down
12 changes: 12 additions & 0 deletions src/tests.cc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -5101,6 +5101,18 @@ void tests::complex_functions()
test(ID_exp)
.expect("18.43908 89145 85774 62∡0.86217 00546 67226 34884ʳ");

step("Complex exponential minus 1 (zero)");
test(CLEAR, "0+0ⅈ expm1", ENTER)
.expect("0+0ⅈ"); // expm1(0) = e^0 - 1 = 0

step("Complex exponential minus 1 (real)");
test(CLEAR, "1+0ⅈ expm1", ENTER)
.match("1\\.71828.*\\+0ⅈ"); // e - 1

step("Complex exponential minus 1 (imaginary)");
test(CLEAR, "0+3.14159265358979323846ⅈ expm1", ENTER)
.match("-2\\..*ⅈ"); // expm1(πi) ≈ -2 (with tiny floating point error)

step("Power");
test(CLEAR, "3+7ⅈ", ENTER, "2-3ⅈ", ID_pow)
.expect("1 916.30979 15541 96293 8∡2.52432 98723 79583 8639ʳ");
Expand Down